I think it was a 13 hour session when me and a friend played through Gears of War all the way from start to finish. An amazing experience.

54hours, for camping lord nagafen in everquest 1 for my epic weapon :p

world of warcraft i think straight two days!

About 30 hours on World of Warcraft. After that my body can just sleep in any position, sometimes with my eyes being open, blink, fe hours later I realize I was sleeping.

cant remember. but i think i spent 10 hours in one day playing Assassin's Creed 2. fuck that game was GOOD.

43 hours of Transport Tycoon. It was 2004, I came out of school and didn't know what the fuck to do with all that time on my hands. So I decided to become a Transport Tycoon trillionaire! It took me more than that session to achieve that though... man, that game is so friggin awesome and addicting as hell...

Also, about 12 hours straight playing Resident Evil 3! I got everything out of that game, played through multiple times and got perfect scores on all bonus levels with hunk and whatnot. (what the hell am I talking? Hunk was in part 2, but it was somethign with mercenaries or soldiers. It's been too long, but you get the whole idea :P) If there would have been platinum trophys back in the day, I would have got that one - twice! Definitely the best entry in the series if you ask me.

There also have been some pretty epic Civilization (2/3/4/5) sessions with my brother, but I never stopped the time on that.

Not even a question. Mother 3, somewhere over 24 hours. I legit started seeing shit. My... "system" had issues saving, and so I decided to play it straight through, out of fear that the if the game wasn't actively being used, it would stop working and I'd lose all my progress. I'm never doing that again. That's actually why I haven't started Nocturne. Saving issues. I can't put myself through that again.

Without cheating, it is probably Dead Rising with 16 hours trying to get that 14-non-stop-playing hours achievement. Had to pause at times, plus loading times, I guess it got up to two hours.

Cheating, and by this I mean giving the controller to a different person (but still watching the game, not leaving or sleeping), almost 50 hours trying to do the whole Gears of War trilogy in co-op (Judgment hadn't released back then). Since we were three dudes, one had to wait a bit before getting the controller, and he could take small breaks like going to the bathroom or getting something to eat. So you could relax the body a bit.

I can't do it more than 4 hours. So much stuff to carry out like gym, office work backlog and other household stuff. My longest was 5 hours way back in Metal Gear Solid 4. 

I played through the whole of Uncharted 3 in one sitting when it came out

So about 8 hours