I am constantly playing World of Warcraft. The endgame is OK but what I really like is leveling. After looking into a bunch of WoW leveling guides recently I decided to try out the Idemise guide and it seems like a good investment.
The guide has directions for getting a character from level 1 to level 70 in 6 days /played. I also know the XP needed to go from 60 to 70 is decreasing around 30% when Wrath of the Lich King ships, so it should be even faster then.
The idemise guide makes the game a lot more fun though — pretty much eliminates time wasted running back and forth between the same areas over and over again, as well as grinding.