I've yet to find one I actually enjoyed my time on. I'm better off getting questions answered by just broadcasting in global chat in-game. The dorks and power-moderators of the channels for games are the same types of dweebs who used to lock forum posts asking questions with "lol search function n00b, LOCKED AND BANNED".
Maybe we need an app that can aggregate all your disparate phpbb2 memberships and notifications. Beeper-style.