I use three types of documentation: POD, mostly for Perl (and C and shell) programs, and only to generate manual pages from. LaTeX for most things that exceeds manual pages (long time ago, I used to use *roff and friends for that). And plain ASCII for anything else (and that's quite a lot).

But to solve the problem of finding the right documentation, you need an index. (La)TeX is good in generating indices.