I will bring the card game "Munchkin". Its fun and easy to learn.
Kill the Monster. Steal the Loot. Stab your Buddy.
http://www.worldofmunchkin.com/game/
I have a quiet a few of the sets.
I could also bring San Juan. Another fun and easy to learn card game.
Besides boardgames/card games. CSS, TF2, and Source Forts =]