TeXtrace is a bundle of Unix scripts that use a freeware boundary tracing package to generate Type 1 outline fonts from Metafont bitmap font outputs. The result is unlikely ever to be of the quality of the commercially-produced Type 1 font, but there remain fonts which many people find useful and which fail to attract the paid experts.
The project was started by Péter Szabó, and its current state is available via the project's entry on Sourceforge and there are already a few sets of fonts on CTAN generated using TeXtrace: Péter Szabó's own EC/TC font set, Vladimir Volovich's CM-Super set, which covers the EC, TC, and the Cyrillic LH font sets, and Takanori Uchiyama's set of the MusixTeX fonts.
A package that says it's "inspired" by TeXtrace is pktrace: this is a small Python program that does the same job~- see http://www.cs.ruu.nl/~hanwen/pktrace/; it has not yet been used to generate fonts that have been installed on CTAN.