Off the top of my head I can think of all the Unreal 3 Engine games, Left 4 Dead, Fallout 3, FEAR 2, SupCom, maybe Demigod as it's another GPG title.
The difference is slight, but in some cases having a quaddie clocked 500mhz slower than a dual gives you the same frame rates. So enough with this "dual cores are better for gaming" nonsense lol.