Fallout 3 about a million times

Pokemon red/blue about 2 million times

halo 3-probably a good 10 times, mostly co-op.

Pokemon Red/Blue-probably 10 times. Some people enjoyed trying to catch them all. But when I was a kid I would always restart as soon as I beat the game and try and beat it again with a completely different team. 

Halo Reach-twice. Once Solo and once Coop

Super Mario Bros-Dozens of times. 

Super Mario World-Dozens of times.

Crash Bandicoot-around 3 times I think.

Wind Waker- Twice

And thats about it, unless you start counting games with pseudo campaigns like mario kart/super smash bros

def jam fight for new york (more than enough times)

FF10 (3 times)

Wrestlemania 21/2000, No Mercy, Smackdown here comes the pain, and every v Raw up until 2009 more then enough times.

Some games from this generation:

• God of War III: 8 times. (9th play-through soon, then 10th before IV releases).
• God of War 1, 2, COO, GOS: 5 times each. (Replaying all soon so it'll be 6 each).
• Gears of War 1: 7 times.
• Gears of War 2: 7 times.
• Gears of War 3: 2 times. (Replaying with a friend on co-op so it'll be 3).
• Mass Effect 1 & 2: 3 times. (Replaying both before I get3, so it'll be 4).
• Alan Wake: 3 times. (Replaying before I get American Nightmare).
• Bioshock 1 & 2: 2 times. (Replaying both before I get Infinite).
• Dante's Inferno = 3 times. (Purely for achievements, also my brother paid me to play it for him for achievements). 
• Castlevania: LOS: 2 times. (Will replay again so it'll be 3).
• The Elder Scrolls IV: Oblivion: 2 times. 
• Fable II: 3 times.

Resident Evil 4 - 13 times (!)
Mass Effect - 6 times
Mass Effect 2 - 5 times
Metroid Prime - 4 times

I beat shining force 2 at least once a year. And thats been since I was 4 or 5. (30 times?)

Most of my NES and SNES games were completed over and over again because back then I didn't have as much money to buy games and a lot more time to play them.

That means games like Mega Man 2 to 6 , Super Mario Bros. 1, 2 & 3, Contra, 2D Zeldas, Super Punch Out!!, etc.. I have completed countless times.

Now if we're talking longer games here's a few I played through more than once:

Final Fantasy IV - 7-8 times
Final Fantasy VI - 7-8 times
Final Fantasy VII - 5 times
Secret of Mana - 4 times
Chrono Trigger - 6-7 times
Resident Evil 2 - 8 times
Resident Evil 4 - 4 times
Uncharted 2 - 4 times

Diablo II : a shitload of times

I love the SMG series. I've completed that and Pikmin several times. ^o^

Mario Karts and 3D Zeldas are the only game series I repeat to beat again.

Although I have beaten New Super Mario Brothers Wii, Super Smash Brothers Melee, and Super Mario 64 multiple times

-Every Numbered Final Fantasy (the least times I've played a numbered one is 3 times, unles you count the recent release of XIII-2 which I've played twice)

-The PS2 & PS3 Tomb Raiders - at least 3 times each

-Soul Reaver series -4 times

-Nier - 3 times (right through all 4 of the story 'refreshes' and what a game/story it is)

-Monster hunter freedom unite (we'll go with hours her as its not really necessarily a chronological game, but a solid 1000 hours overall for sure)