Ooh I love Munchkin! It's like D&D but now you have an excuse to powergame, kick down the door, kill the enemy, and snaff treasure. It was created for people who don't like the roleplay, storyline aspect of D&D (NOT that I count myself one of their number, but sometimes it's fun just to kill stuff.)
Also play a lot of scrabble, Carcassone and Citadels. A game we've just bought is called Lost Cities, which is good fun - you need to be able to card count on a very basic level, though.
Last time I got together with some RPG freinds we played a game - I think it was called Guillitine, not sure, but that was pretty good too.