Conversion between (La)TeX and others

troff
troff-to-latex, written by Kamal Al-Yahya at Stanford University (California, USA), assists in the translation of a troff document into LaTeX format. It recognises most -ms and -man macros, plus most eqn and some tbl preprocessor commands. Anything fancier needs to be done by hand. Two style files are provided. There is also a man page (which converts very well to LaTeX...). The program is copyrighted but free. tr2latex is an enhanced version of this troff-to-latex.

WordPerfect
wp2latex has recently been much improved, and is now available either for MSDOS or for Unix systems, thanks to its current maintainer Jaroslav Fojtik.
PC-Write
pcwritex.arc is a print driver for PC-Write that "prints" a PC-Write V2.71 document to a TeX-compatible disk file. It was written by Peter Flynn at University College, Cork, Republic of Ireland.
runoff
Peter Vanroose's rnototex conversion program is written in VMS Pascal. The sources are distributed with a VAX executable.
refer/tib
There are a few programs for converting bibliographic data between BibTeX and refer/tib formats. The collection includes a shell script converter from BibTeX to refer format as well. The collection is not maintained.
RTF
Rtf2tex, by Robert Lupton, is for converting Microsoft's Rich Text Format to TeX. There is also a convertor to LaTeX by Erwin Wechtl, called rtf2latex. The latest converter, by Ujwal Sathyam and Scott Prahl, is rtf2latex2e; this system seems rather good already, and is still being improved.

Translation to RTF may be done (for a somewhat constrained set of LaTeX documents) by TeX2RTF, which can produce ordinary RTF, Windows Help RTF (as well as HTML, conversion to HTML). TeX2RTF is supported on various Unix platforms and under Windows 3.1

Microsoft Word
A rudimentary program for converting MS-Word to LaTeX is wd2latex, for MSDOS; a better idea, however, is to convert the document to RTF format and use one of the RTF converters mentioned above.
Excel
Excel2Latex converts an Excel file into a LaTeX tabular environment; it comes as a .xls file which defines some Excel macros to produce output in a new format.

A separate FAQ by Wilfried Hennings deals specifically with conversions between TeX-based formats and word processor formats may be referred to for more detailed information.

A group at Ohio State University (USA) is working on a common document format based on SGML, with the ambition that any format could be translated to or from this one. FrameMaker provides "import filters" to aid translation from alien formats (presumably including TeX) to FrameMaker's own.

excel2latex
support/excel2latex/xl2latex.zip
pcwritex.arc
support/pcwritex.tar.gz
refer and tib tools
biblio/bibtex/utils/refer-tools.tar.gz
rnototex
support/rnototex.tar.gz
rtf2latex
support/rtf2latex.tar.gz
rtf2latex2e
support/rtf2latex2e.tar.gz
rtf2tex
support/rtf2tex.tar.gz
tex2rtf
support/tex2rtf.tar.gz
tr2latex
support/tr2latex.tar.gz
troff-to-latex
support/troff-to-latex.tar.gz
wd2latex
dviware/wd2latex.tar.gz
wp2latex
support/wp2latex.tar.gz
Word processor FAQ
http://www.tug.org/utilities/texconv/index.html
Word processor FAQ (source)
help/wp-conv/wp-conv.zip