Not much.

PS2

Resident Evil 4
Smackdown! vs. Raw 2006
Smackdown! vs. Raw
Smackdown! Here Comes the Pain
State of Emergency
Star Wars Battlefront 2
The Simpsons Road Rage
Cabela's Big Game Hunter
Whiplash
Soul Calibur 2

i only own a PS(1?) and play the same three games endlessly - EA MLB, EA NCAAFootball and EA FIFA Soccer. . . sad but it keeps me entertained

-Madden '06
-MLB:The Show
-NBA Live '06
-NHL '06
-Fight Night Round 3
-Smackdown vs. Raw '06
-Arena Football
-MVP '06 NCAA Baseball
-Star Wars:Empire at War

I have a decent collection. Not as many as I once did (you'd be surprised how much some collectors are willing to spend on old worn out PS1 games) but still a good amount, I think.

PS1/PS2
Resident Evil 1-Code Veronica
Silent Hill 1-3
Fatal Frame 1 and 2
Disgaea: Hour of Darkness
Phantom Brave
Makai Kingdom
Shadow Hearts 1 and 2
Digital Devil Saga
Final Fantasy 7-10 (and Tactics)
Front Mission 3
Soul Calibur 2
Guilty Gear: Isuka
Star Ocean 3
Kuon

GC:
Metroid Prime
Tales of Symphonia
Skies of Arcadia
Eternal Darkness
Resident Evil 4
Baten Kaitos

PC:
Half Life
Warcraft 3
Diablo 2
Homeworld
Baldur's Gate
Icewind Dale
Neverwinter Nights

Ps2:
Silent hill 2,3 and 4
Metal gear solid 2 and 3
Fatal Frame and second part:crimson butterfly
Final fantasy X
GTA Vice city and Sant Andreas

PS
Metal gear solid
Silent Hill