While Diablo 3 doesn't arrive, how about getting your Windows 7 in the mood while you wait for its launch?
MotioninJoy offline configuration tool for Playstation 3 controls.
If offline GTA: San Andreas is already fun, then imagine playing against your friends or other players around the world.
Utility for organizing mods in different games.
Famous map of Warcraft 3.

Play classics like Doom, Heretic and Hexen to the fullest.