OTeX
- Plain TeX macros for automatic referencing, equation and theorem numbering, figures, and indexing, and other typesetting tasks. Flexible enough to handle cross referencing for books. By Peter Olver.
- http://www.math.umn.edu/~olver/otex.html

Eplain
- A set of TeX macros that expands on and extends the definitions in plain TeX, written by Karl Berry, Steve Smith and others. Downloads and mailing list.
- http://www.ccs.neu.edu/home/dorai/eplain/