Steve Jackson Games produced all kinds of stuff but probably their best selling Munchkin is the most well known. I played this with 2 gaming friends last week and really enjoyed it.
Munchkin is a card game in which the players are characters exploring and looking to plunder a dungeon. If you have ever played a role-playing game, especially Dungeons & Dragons, this is familiar teritory. However, this game is not for serious RPGer’s as it is a silly spoof of the genre with hilarious weapons, powers and characters.
It is easy to get into and lots of fun.