Here's what I've got and would be willing to play...
Blur
Borderlands +1
Company of Heroes
DoW2
Dungeon Defenders +1
Frozen Synapse
LotR: Battle for Middle Earth (1 or 2)
Monday Night Combat +1
Portal 2 (I've never played co-op)
Red Faction: Guerrilla
Serious Sam HD (1 or 2)
Starcraft 1
Swords and Soldiers HD
Demigod -1 :-)
CoD:World at War or Black Ops Nazi Zombies +1
Oh yea, will there be a TF2 server? If so make sure you remove spawn time. I seems to work better at LANs that way.