I decided I'm going to keep editing this same post when I add something new, so you won't have to parse all the comments to find the newest features:
Very new: Site Search powered by Google.
Recently new: I just enabled polls. I haven't tested it yet. I'm not even sure where they show up. You'll find them under "create content" link. I'm going to go try one now. If they work, Paul can use this to create a poll so we can vote on the tracks for BassIAB.