You need to immerse yourself in a game in order to forget. So yes an MMO like WOW would do the trick, or if you like sports, try a Pro Evo online or Madden, don't know how good that one is, but you'll spend hours playing against other people in Pro Evo.
Aside from those type of competitive games, you need games with a strong sense of universe, like movies, that's what does the trick for me. Love to immerse myself in a game like The Witcher, NeverWinter Nights 2 (and Mask of the Betrayer), Knights of the Old Republic, etc
Because they are long games that create an attachment between you and the characters and the world, and you just forget. But Gears of War 2, Fallout 3, Bioshock, Mass Effect...
Those are all games that do a good job of drawing you in their world. Personally? You should just download all seasons of Entourage and Battlestar Galactica and call it a day.