The Daily Grind: Do you have a fallback MMO?

My first fallback MMO, though I'd not have called it that at the time, was Ultima Online. Whenever I got sick of EverQuest or Dark Age of Camelot, I found myself wandering back to my houses in Britannia. World of Warcraft took over for a while, and then Star Wars Galaxies (yes, post-post-NGE) became my safe MMO -- the world to which I could retreat after a particularly nasty break-up with the latest and greatest themepark shiny, something that seemed to happen with increasing frequency as post-WoW games rushed to launch and left me wanting more.