Rome: Total War
Sid Meier's Pirates (for a short stress-removing pillaging marathon)
MOO2 or GalCiv2 (depending on mood)

Morrowind.

Sacred 2.

Played on PS3 at least 150 hrs on one character, and I don't know how much more on 2 others. Just bought the Gold edition off Steam and even though I've got dozens of games to play, I've already played 3-5 hrs of Sacred 2.

I recently beat and uninstalled both Diablo 3 and Torchlight 2. Neither held my interest for very long. But Sacred 2 keeps grabbing me back.