I use occasionally
txt2tags when a quick html output is required. Normally I use
TeX for writing papers. I would suggest you also check
Pandoc which is written in
Haskell. You can install it on OpenBSD using
Cabal Haskell package manager since Pandoc is not in ports. Cabal is in
ports and works very well on OpenBSD. Pandoc converts multiple documen (light mark up) formats into each other. For man pages I would use
mandoc and mdoc macros written by Kristaps Dzonsons. Unlike Groff it supports html, PosrScript outputs and of course has beautiful Ascii output. Of course mandoc just like Groff and TeX is full blown text typing system and it doesn't have light learning curve. I will finish this post with the remark that TeX (my bread and butter) is not designed for Ascii or even HTML output. Man pages is one of those rare instances (besides Music for which I use LilyPond) where TeX is not a right tool for the job.