Besides MGS4 I'd say Uncharted, the Orange Box and GTA4(if you don't have them on 360), Resistance:FOM and Socom. Socom is freakin addicting. Best console based multiplayer I've tried.
PSN: EDguila
PS3 library: Motorstorm, Assasin's Creed, Orange Box, Uncharted:DF, Metal Gear Solid 4, Resistance:FOM, Rachet & Clank Future:ToD,
Near future: Folklore, SOCOM Confrontation, BioShock, Little Big Planet, Resistance 2.