I got my wife addicted to the board game Zombies! and its expansion packs. We also bought Humans!, in which you play as the zombies, but the rules are absolutely horrible. We're currently working on changing the rules to make the game playable because, com on, who wouldn't want to play as a brain-eating zombie at some point?
Over the years, I played and ran RPG's in the universes of AD&D, Star Wars, Twerps, Gamma World, Marvel Super Heroes, and certain systems that my friend and I made up.
Currently, I've been playing Friday Night Fights, Legends of Wrestling, and Mythic, mostly because all three systems can be played solo.