World of Warcraft: Cataclysm. If you're currently rolling through Azeroth, owning fools while playing as a Death Knight, Hunter, Priest, Rogue, Shaman, Warlock or Warrior, you can get an early glimpse at some of the new powers and revamped mechanics the expansion will bring your way.
If you're having a hard time understanding what all these changes really mean, we suggest checking out our loot-obsessed sister site, WoW.com, for a detailed analysis of these changes. For instance, we just learned that the Rogue's new "Smoke Bomb" ability will change them from merchants of death into invisible merchants of death. How fun!