I'm a big fan of the Yahoo! Design pattern library. I'm surprised there isn't one for game UI - or at least I don't know of one. Does anyone? Looking for patterns for leaderboards, etc.
As DA01 pointed out , Game design patterns vary wildly and there is hardly a defined standard behind how to best do things. But here is a collection of some of the stuff I found
The unfortunate thing is none of these are really proper pattern libraries but can give you some guidelines into best practices for Game UI design