I initially found AI War from the RPS article(s) mentioned earlier, didn't think about it for a while, got the demo, procrastinated, tried the demo, bought the game + expansions (around the time Spire was released) in a massive Steam sale, and now here I am.
Tunngle seems interesting, with a far more friendly (albeit still rough) interface compared to Comodo. I personally think the IRC channel is the best place to hang out, but that's more because I already regularly visit IRC channels anyways.
I think I'll hang around in the Tunngle channel for a while, and see how well it works.