What non-recently-released shooters are you still playing online?

I know communities can drop like a rock, but it's hard to know which games are still going strong, short of trying it myself.  So, what's still keeping you online? 
 
(I booted up Syndicate tonight and was able to jump right in.  Thinking of getting back into the Killzone 3 multiplayer, or finally trying Uncharted 3.)