Choice of scalable outline fonts

If you are interested in text alone, you can use any of over 20,000 fonts(!) in Adobe Type 1 format (called 'PostScript fonts' in the TeX world and 'ATM fonts' in the DTP world), or any of several hundred fonts in TrueType format. That is, provided of course, that your previewer and printer driver support scalable outline fonts.

TeX itself only cares about metrics, not the actual character programs. You just need to create a TeX metric file TFM using some tool such as afm2tfm (possibly in combination with vptovf), afmtotfm (from Y&Y, see commercial implementations) or fontinst. For the previewer or printer driver you need the actual outline font files themselves (pfa for Display PostScript, pfb for ATM on IBM PC, Mac outline font files on Macintosh).

If you also need mathematics, then you are severely limited by the demands that TeX makes of maths fonts (for details, see the paper by B.K.P. Horn in TUGboat 14(3)). For maths, then, there are relatively few choices (though the list is at last growing). There are several font families available that are based on Knuth's original designs, and some that complement other commercial text font designs; one set (MicroPress's 'informal math') stands alone.

Computer Modern
(75 fonts - optical scaling) Donald E. Knuth
The CM fonts were originally designed in Metafont, but are also now available in scalable outline form. There are commercial as well as public domain versions, and there are both Adobe Type 1 and TrueType versions. A set of outline versions of the fonts was developed as a commercial venture by Y&Y and Blue Sky Research; they have since assigned the copyright to the AMS, and the fonts are now freely available from CTAN. Their quality is such that they have become the de facto standard for Type 1 versions of the fonts.
AMS fonts
(52 fonts, optical scaling) The AMS
This set of fonts offers adjuncts to the CM set, including two sets of symbol fonts (msam and msbm) and Euler text fonts. These are not a self-standing family, but merit discussion here (not least because several other families mimic the symbol fonts). Freely-available Type 1 versions of the fonts are available on CTAN. The eulervm package permits use of the Euler maths alphabet in conjunction with text fonts that do not provide maths alphabets of their own (for instance, Adobe Palatino or Minion).
Computer Modern Bright
(62 fonts - optical scaling) Walter Schmidt
CM Bright is a family of sans serif fonts, based on Knuth's CM fonts. It comprises the fonts necessary for mathematical typesetting, including AMS symbols, as well as text and text symbol fonts of various shapes. The collection comes with its own set of files for use with LaTeX. The CM Bright fonts are supplied in Type 1 format by MicroPress, Inc.

For further details (including samples) see
http://www.micropress-inc.com/fonts/brmath/brmain.htm

Concrete Math
(25 fonts - optical scaling) Ulrik Vieth
The Concrete Math font set was derived from the Concrete Roman typefaces designed by Knuth. The set provides a collection of math italics, math symbol, and math extension fonts, and fonts of AMS symbols that fit with the Concrete set, so that Concrete may be used as a complete replacement for Computer Modern. Since Concrete is considerably darker than CM, the family may particularly attractive for use in low-resolution printing or in applications such as posters or transparencies. Concrete Math fonts, as well as Concrete Roman fonts, are supplied in Type 1 format by MicroPress, Inc.

For further information (including samples) see
http://www.micropress-inc.com/fonts/ccmath/ccmain.htm

BA Math
(13 fonts) MicroPress Inc.
BA Math is a family of serif fonts, inspired by the elegant and graphically perfect font design of John Baskerville. BA Math comprises the fonts necessary for mathematical typesetting (maths italic, math symbols and extensions) in normal and bold weights. The family also includes all OT1 and T1 encoded text fonts of various shapes, as well as fonts with most useful glyphs of the TS1 encoding. Macros for using the fonts with Plain TeX, LaTeX 2.09 and current LaTeX are provided.

For further details (including samples) see
http://www.micropress-inc.com/fonts/bamath/bamain.htm

HV Math
(14 fonts) MicroPress Inc.
HV Math is a family of sans serif fonts, inspired by the Helvetica (TM) typeface. HV Math comprises the fonts necessary for mathematical typesetting (maths italic, maths symbols and extensions) in normal and bold weights. The family also includes all OT1 and T1 encoded text fonts of various shapes, as well as fonts with most useful glyphs of the TS1 encoding. Macros for using the fonts with Plain TeX, LaTeX 2.09 and current LaTeX are provided. Bitmapped copies of the fonts are available free, on CTAN.

For further details (and samples) see
http://www.micropress-inc.com/fonts/hvmath/hvmain.htm

Informal Math
(7 outline fonts) MicroPress Inc.
Informal Math is a family of fanciful fonts loosely based on the Adobe's Tekton (TM) family, fonts which imitate handwritten text. Informal Math comprises the fonts necessary for mathematical typesetting (maths italic, maths symbols and extensions) in normal weight, as well as OT1 encoded text fonts in upright and oblique shapes. Macros for using the fonts with Plain TeX, LaTeX 2.09 and current LaTeX are provided.

For further details (including samples) see
http://www.micropress-inc.com/fonts/ifmath/ifmain.htm

Lucida Bright with Lucida New Math
(25 fonts) Chuck Bigelow and Kris Holmes
Lucida is a family of related fonts including seriffed, sans serif, sans serif fixed width, calligraphic, blackletter, fax, Kris Holmes' connected handwriting font, etc; they're not as 'spindly' as Computer Modern, with a large x-height, and include a larger set of maths symbols, operators, relations and delimiters than CM (over 800 instead of 384: among others, it also includes the AMS msam and msbm symbol sets). 'Lucida Bright Expert' (14 fonts) adds seriffed fixed width, another handwriting font, smallcaps, bold maths, upright 'maths italic', etc., to the set. The distribution includes support for use with Plain TeX \acro{PSNFSS} (\Qref{}{Q-usepsfont}) PSNFSS thanks to Sebastian Rahtz and David Carlisle.

For a sample, see http://www.YandY.com/download/chironlb.pdf

MathTime 1.1
(3 fonts) Publish or Perish (Michael Spivak)
The set contains maths italic, symbol, and extension fonts, designed to work well with Times-Roman. These are typically used with Times, Helvetica and Courier (which are resident on many printers, and which are supplied with some PC versions). In addition you may want to complement this basic set with Adobe's Times Smallcap, and perhaps the set of Adobe 'Math Pi' fonts, which include blackboard bold, blackletter, and script faces.

For a sample, see http://www.YandY.com/download/chironmt.pdf

MathTime Plus
(12 fonts) Publish or Perish (Michael Spivak)
Adds bold and heavy versions of the basic math fonts, as well as upright math "italic". There are also Greek letters for use in typesetting terms commonly used in physics, as well as regular and bold script faces. Both MathTime distributions include support for use with Plain TeX and LaTeX 2.09 (including code to link in Adobe Math Pi 2 and Math Pi 6). Support under LaTeX2e is provided in PSNFSS thanks to Frank Mittelbach and David Carlisle.

For a sample, see http://www.YandY.com/download/mathplus.pdf

TM Math
(14 fonts) MicroPress Inc.
TM Math is a family of serif fonts, inspired by the Times (TM) typeface. TM Math comprises the fonts necessary for mathematical typesetting (maths italic, maths symbols and extensions) in normal and bold weights. The family also includes all OT1 and T1 encoded text fonts of various shapes, as well as fonts with most useful glyphs of the TS1 encoding. Macros for using the fonts with Plain TeX, LaTeX 2.09 and current LaTeX are provided. Bitmapped copies of the fonts are available free, on CTAN.

For further details (and samples) see
http://www.micropress-inc.com/fonts/tmmath/tmmain.htm

Belleek
(3 fonts) Richard Kinch
Belleek is the upshot of Kinch's thoughts on how Metafont might be used in the future: they were published simultaneously as Metafont source, as Type 1 fonts, and as TrueType fonts. The fonts act as "drop-in" replacements for the basic MathTime set (as an example of "what might be done").

The paper outlining Kinch's thoughts, proceeding from considerations of the 'intellectual' superiority of Metafont to evaluations of why its adoption is so limited and what might be done about the problem, is to be found at http://truetex.com/belleek.pdf (the paper is a good read, but exhibits the problems discussed in "getting good PDF" - don't try to read it on-screen in Acrobat reader).

PA Math
PA Math is a family of serif fonts loosely based on the Palatino (TM) typeface. PA�Math comprises the fonts necessary for mathematical typesetting (maths italics, maths, calligraphic and oldstyle symbols, and extensions) in normal and bold weights. The family also includes all OT1, T1 encoded text fonts of various shapes, as well as fonts with the most useful glyphs of the TS1 encoding. Macros for using the fonts with Plain TeX, LaTeX 2.09 and current LaTeX are provided.

For further details (and samples) see
http://www.micropress-inc.com/fonts/pamath/pamain.htm

mathpazo version 1.003
(5 fonts) by Diego Puga
The Pazo Math fonts are a family of type 1 fonts suitable for typesetting maths in combination with the Palatino family of text fonts. Four of the five fonts of the distribution are maths alphabets, in upright and italic shapes, medium and bold weights; the fifth font contains a small selection of "blackboard bold" characters (chosen for their mathematical significance). Support under LaTeX2e is available in PSNFSS; the fonts are licensed under the GPL, with legalese permitting the use of the fonts in published documents.
pxfonts set version 1.0
(26 fonts) by Young Ryu
The pxfonts set consists of The text fonts are available in OT1, T1 and LY1 encodings, and TS encoded symbols are also available. The sans serif and monospaced fonts supplied with the txfonts set (see below) may be used with pxfonts; the txfonts set should be installed whenever pxfonts are. LaTeX, dvips and PDFTeX support files are included. The documentation is readily available.

The fonts are licensed under the GPL; use in published documents is permitted.

txfonts set version 3.1
(42 fonts) by Young Ryu
The txfonts set consists of The text fonts are available in OT1, T1 and LY1 encodings, and TS encoded symbols are also available. LaTeX, dvips and PDFTeX support files are included. The documentation is readily available.

The fonts are licensed under the GPL; use in published documents is permitted.

Adobe Lucida, LucidaSans and LucidaMath
(12 fonts)
Lucida and LucidaMath are generally considered to be a bit heavy. The three maths fonts contain only the glyphs in the CM maths italic, symbol, and extension fonts. Support for using LucidaMath with TeX is not very good; you will need to do some work reencoding fonts etc. (In some sense this set is the ancestor of the LucidaBright plus LucidaNewMath font set.)
Proprietary fonts
Various sources.
Since having a high quality font set in scalable outline form that works with TeX can give a publisher a real competitive advantage, there are some publishers that have paid (a lot) to have such font sets made for them. Unfortunately, these sets are not available on the open market, despite the likelihood that they're more complete than those that are.
Mathptm
Alan Jeffrey, Walter Schmidt and others.
This set contains maths italic, symbol, extension, and roman virtual fonts, built from Adobe Times, Symbol, Zapf Chancery, and the Computer Modern fonts. The resulting mixture is not really entirely acceptable, but can pass in some circumstances. The real advantage is that the mathptm fonts are (effectively) free, and the resulting PostScript files can be freely exchanged. Support under LaTeX2e is available in PSNFSS.
The very limited selection of commercial maths font sets is a direct result of the fact that a maths font has to be explicitly designed for use with TeX and as a result it is likely to lose some of its appeal in other markets. Furthermore, the TeX market for commercial fonts is minute (in comparison, for example, to Microsoft TrueType font pack #1, which sold something like 10 million copies in a few weeks after release of Windows 3.1!).

Text fonts in Type 1 format are available from many vendors including Adobe, Monotype, Bitstream. Avoid cheap rip-offs: not only are you rewarding unethical behaviour, destroying the cottage industry of innovative type design, but you are also very likely to get junk. The fonts may not render well (or at all under ATM), may not have the 'standard' complement of 228 glyphs, or may not include metric files (needed to make TFM files).

TrueType remains the "native" format for Windows. Some TeX implementations such as TrueTeX use TrueType versions of Computer Modern and Times Maths fonts to render TeX documents in Windows without the need for additional system software like ATM.

When choosing fonts, your own system environment may not be the only one of interest. If you will be sending your finished documents to others for further use, you should consider whether a given font format will introduce compatibility problems. Publishers may require TrueType exclusively because their systems are Windows-based, or Type 1 exclusively, because their systems are based on the early popularity of that format in the publishing industry. Many service bureaus don't care as long as you present them with a finished print file for their output device.

CM family collection
Browse fonts/cm/ps-type1/bluesky/
AMS font collection
Browse fonts/amsfonts/ps-type1/
Belleek fonts
fonts/belleek/belleek.zip
eulervm.sty and supporting metrics
fonts/eulervm.tar.gz
hvmath (free bitmapped version)
fonts/micropress/hvmath.tar.gz
pxfonts
fonts/pxfonts.tar.gz
tmmath (free bitmapped version)
fonts/micropress/tmmath.tar.gz
txfonts
fonts/txfonts.tar.gz