almost half a year ago I had a brief mail thread with Ken regarding documentation of the Mantis database; he suggested to send mail to this forum, doing herewith slightly delayed :-)
What I can offer in case you are interested is fully documenting (with your input) the database model of Mantis. Result will be full web documentation (*.html) and MS Word document (*.rtf). We use Mantis for our internal software development at my employer, and we use it massively in our group(s). My developers and our internal clients love it, so why not give something back in return? I'd love to help development by contributing that material.
So, interested? If so I can provide some basic examples before putting full work in. I'd do a basic reverse engineering of the DB with hardly any table or variable comments, but still the result should be good.