I think that having a wiki that is consistently available and has several active members is crucial. ATM, the only other feature that I can see a need for is a forum so that we don't clutter the larian forums with threads like this one. And to make it easier to spot weresheep.net-specific threads among the much higher number of threads here.
Any additional functionality right now would probably be premature. We should prepare to fulfill the community's unmet needs as they arise, but there is no way to know what those needs will be yet.
If anything, selecting a flexible and well-rounded CMS now could save time later (Drupal comes to mind, but it has been a long time since I administered a CMS, so there might be much better options)
Also, consider that features like teamspeak can become fairly expensive (at least compared to text with a few images).
