We need to get this group active, maybe we can get and inhouse going or something. Also if you have invite: send them out soon, DotA 2 is going into full release soon and you invites will go ByeBye and DotA 2 will become a 1st come 1st served and will be a pain to get in very quickly. Even if your friends say they won't play it (IE they play LoL) tell them just to add it to their steam library (it counts as a bought game for the community if they wanted to add friends themselves in TF2 or other F2P steam games).

TL;DR:
Lets get active; send your DotA2 invites out and have them redeemed, soon.