Deffo inFamous too, probably over 150h, stupid trophy, but I liked every drop of it. Then it's Burnout and then God Of War 3.

Multi it's Killzone 2 (over 150h), COD MW2 and the third one probably Black Ops.

I was gonna say DQIX with 125 hours or so since I've been playing it a lot recently, but then I opened my Pokemon Version Diamant:

DUREE DE JEU 652:55

...wow. And plenty of games like Pokemon Mystery Dungeon probably rival it, but I can't tell how many hours I've put together on those since I replay them all the time.

World of Warcraft by far.  Probably more than the next 50 games combined.  Actually, there is a very good chance I played it more than every single game this generation combined.

After that would probably be Bad Company 2 or Team Fortress 2, with everything else under 100 hours most likely.  There might be some stuff early in the gen I don't remember, I probably played CoD4 quite a bit.

Hundreds of hours

1. Heroes of Newerth (Going to be the only game ever that I spend over 1000hours playing eventually. So sad)

2. Halo 3

3. Left 4 Dead

4. Team Fortress 2

50-99 hours

5. fallout 3

6. minecraft

7. elder scrolls IV

8. Dragon Quest Monster Joker

20-49hours

9. Grand Theft Auto 4

10. Pokemon Platinum 

11. The World Ends With You

12. Left 4 Dead 2

13. Halo Reach

Single PLayer: Mass Effect, Assassin's Creed 2, Assassin's Creed Brotherhood, Uncharted 2, Portal 2

Multiplayer: Modern Warfare 2 (400 Hrs), Black Ops (Blah 35 Hrs), Uncharted 2 (25)

Super Smash Bros. Brawl (800 hours), Super Mario Strikers Charged (>300), and Goldeneye 007 wii (>250)

I have just over 300 hours combined for all my DS Pokemon games

BEST FRIGGIN GAME EVER!!!

Fire Emblem: Radiant Dawn

200-300

Pokemon D/P

Animal Crossing WW

100-199

Mass Effect

Mass Effect 2

Oblivion

Pokemon B/W

Pokemon HG/SS

SSBB

FF Tactics Advance 2

WarioWare D.I.Y

Tales of Vesperia

50-99

Lost Odyseey 

Etrian Odyseey 3

MineCraft

DQ9

SMT: Devil Survivor

Chrono Trigger

AOE 3