Like stated previously, all of the CoD's if not all, and I can't think straight right now, but i'm pretty sure that most racing games have co-op offline game modes. It all comes down to which game genre you're into. Thinking about it, I think all family games are like that, well if you're into that.
Borderlands! is epic borderlands 2 comes out in september that also looks very epic and borderlands has 2 play co-op and number 2 has 4 player co-op
Resident Evil 5<3
Splinter Cell Conviction
Gears of War 2
Army of 2
Um I totally know more, I'm just kinda drawing a blank =/
Halo. One of the CODs has co-op, I think it was world at war, not sure.
Yea XD those are pretty much the only ones we know of.
for ps3 i think unchrted 3 is a good co-op
Any of the CODs and Kilzone 3.