This was my own solo project from 1994 through 2000, and then for a few more years, it was nobody's project. Since then, Kathryn Andersen has made wonderful and much-needed improvements. The project is now mantained by her and is hosted at Sourceforge:
Go there for the latest version. For historical interest and just in case someone needs it, you can still get my own last release of txt2html, which was version 1.28, released on 23 May 2000.
Also of note is txt2tex, a text to LaTeX converter by Kalvis M. Jansons, based on txt2html.