Steam

lists and buddy finding, along with a server browser for classic and ever-popular VALVe games (most notable being Counter-Strike), but you also get access to exclusive VALVe content like Half-Life 2 videos. Steam will replace the old WON id's for games like Half-Life. and if you have a valid cd key from a VALVe software title, you'll still have access to the gamut of VALVe game updates and other media.
This is the official first full release of VALVe's popular multimedia software platform. Steam is like a cross between Gamespy and something good. Not only do you get instant messaging, buddy