Great Steam game??

Ok I was looking for a new Steam game, cause I got money to spare. Besides the basics (orange box, CSS, DoDS and stuff which I already have) what is good? I was looking at Sam and Max, the Dracula games, and Beyond Good and Evil. Am I missing anything? are any of these games good? I already have Audiosurf too.

At this point, the question is more what great games aren't on Steam.

id collection
Rockstar Collection
Sam and Max seasons 1 and 2
Dawn of War
Company of Heroes
Civilization 4
Deus Ex
Grid
Medieval 2
Call of Duty 2
S.T.A.L.K.E.R

The list goes on and on and on and on and on and on and on and on and on...

Man there are so many good games on Steam these days. If I had to choose one then it would without a doubt be Vampire the Masquerade : Bloodlines.

Absolutely unparalleled , get it now.

My recommendation if you have alot of music is Audiosurf. If you want something different try Darwinia. Also yes, get Pyschonauts and Beyond Good and Evil.