Halo 3 is coming out soon, and leaked Halo 3 screens was posted by me couple of days ago, I will give the URL for that at the end, however, if you haven't still finished Halo, or haven't see everything that there is to see in Halo, here is your chance.
Halo is a Xbox 360 game, and a brilliant one, I enjoyed to very much, and recommend it to anyone,

http://www.xomba.com/user/15016/xtrack, where you can find Halo 3 screens.

Halo walkthrough here: