Hey man. Good purchase. Now that you are 4 years in, there are TONS of games to lose yourself with. God bless you, here we go:
Exclusive
Uncharted 2
Killzone 2/3
Infamous
Metal Gear Solid 4
God of War 3
Demon's Souls
Heavy Rain
Little Big Planet 2
Multi-Platform
Bioshock (the 1st is 10x better than the 2nd)
Batman: Arkham Asylum
Assassin's Creed 2/Brotherhood
Mass Effect 2 (includes all mission DLCs except "Arrival" that just came out)
PSN (exclusive or not)
Dead Nation
Flower
Lara Croft & the Gaurdian of Light
There are tons of other games. Also, make sure you are aware of what is coming out this year on the ps3, it has many of its powehouse franchises releasing, such as Uncharted 3, Twisted Metal, Resistance 3, The Last Guardian, Dark Souls and some non-exlcusives like Batman: Arkham City
You're about to become a hermit...
