God damnit. I just bought Spec Ops: The Line and State of Decay: Lifeline.
Just as I was starting to make progress with my 360 backlog...
I've actually been playing lots of different XBLA games lately:
Fable Heroes:
An OK game. Tons of wasted potential....the music was nice though. It reminded me of Banjokazooie at times.
I tried to find the music tracks on youtube, but it doesn't seem like it's a particularly popular game.
Joe Danger: The Movie
I kind of understand why people didn't like it as much as the first one, but I enjoyed it enough to 400/400 it.
Really frustrating at times, but not so hard that it's impossible.
Battleblock Theater:
Fun game, but it didn't grab me as much as Castle Crashers. I finished the main story and got the first (?) ending.
I doubt I'll go back to it unless they port it to current gen consoles.
Trine 2:
Played through a few levels in co-op with one of my friends. One of the most fun co-op experiences I've had in while.
I don't want to finish the game in solo mode now.
Charlie Murder:
I'm currently playing through CM. I really like what I've played so far.

Not sure if I like it as much as I liked Castle Crashers, but it's a decent game to play if you have grown tired of CC.
Next up after Charlie Murder: CoJ: Gunslinger or State of Decay.