I don't know the exact numbers, but I would assume my top games would be Battlefield 1942, Call of Duty 4, Oblivion, and Mercenaries (seriously).
The games I been playing the most lately is the DMC collection and mothafucking Sniper:Ghost warrior.
In this game you gots to keep silent and proceed within the jungle parameters with a sniper rifle, while killing off your targets from a far distance. You have to use the bushes and the trees in order to increase your level of survival. You must become the hunter instead of the hunted.
I thought my 147 hours of Persona 4 was a lot, but it's nothing compared to some of the playtimes in this thread.
My Peggle time isn't tracked but if you were to add it all up across all the (many) computers, tablets, and phones I play that on it would probably be over 200 hours.
Pokemon main franchise games - many, many years
Super Smash Bros Melee - I dunno a LOT
CounterStrike Source - 151 hours
Disgaea 1 - 155 hours
CounterStrike 1.6 - 197 hours
League of Legends - 221 hours
Team Fortress 2 - 500+ atleast
F.E.A.R. - 583 hours
Age of Mythology - lifetime over a 1000
How on earth do I still have a life?