Can Someone Recommend Some Good Co-op Games on The Xbox 360?

Anyone know any good co-op 360 games for the xbox 360?

So far I've played I've played RE5 and the Gears of Wars series. I want a game where two people cango online on one console. Any recommendations?

Halo 3 and Halo ODST.

Army of Two, either one

Splinter Cell Conviction, Left 4 Dead 1 and 2, Borderlands