Having pretty much crushed Arkham City, I decided to try a multiplayer FPS. Downloaded the MMOFPS Planetside 2 last night but haven't had a chance to play it yet. Everything I'm reading about it seems like it should be a good time killer for a bit.
It's like Battlefield 3 (lots of vehicles, air and ground, different classes you can spawn as) set in the future but it has a consistent world, so eventually one of the 3 factions will take control of the entire planet.
It's free to play - which is a model I usually despise - but doesn't appear to have the really restrictive lockouts that a game like Star Wars MMORPG does, everything that you can pay for you can also 'earn' by playing the game for free.
I'll keep you guys updated on what faction and server I roll on in case you want to squad up.