There are two possibilities:

-One likes a modification and browses its hosted forum and will spot vacancies.
-One is a coder or artist who is willing to spend some time on a modification for M2TW/RTW, it doesn't matter much which for those people and they don't browse all forums.

A central place may work. Keep the vacancy forum clean please, do not create multiple topics for the same modification. Best may be to update the first post (the forum is setup in such a way that the first post is always listed on the top of every page in the topic).

Thank you for the idea oscarreeve.