Suggest some good free multiplayer games.

So I'm getting kind of bored of JUST playing LoL and the odd bit of Spiral Knights and I've quit WoW until the next expansion (Yeah I know it's not free, but it's the not playing it part that's important)
Can anybody suggest, any GOOD free to play multiplayer games?

I don't care what genre it is, as long as it isn't like, puzzle or something crap like that. Not that I don't like a good puzzle game, it's just, yeah you get what I mean.

Pic not related.