Among one of the few good online FPS's on the market right now there is this game called Blacklight: Tango Down.
It isn't exactly Call of Duty Black Ops, but if you somehow want to take a break from the COD franchise and try something new Flashlight is the way to go!
It has been released in July for all platforms(PC, PS3, Xbox 360) and even though it couldn't compete with Black Ops, it still keeps it's player base alive.
The game is made for multiplayer. It has also a co-op mode but with no storyline at all.
It stands out by offering the Hyper Reality Visor which is practicly a device that allows you to see people through walls for a short(very short) period of time.
This mecanic can be countered by the use of special grenades that when they explode they create an EMP field among them thus players with the HRV can only see static there.
This mecanic is the strong point of the game, setting it appart from Call of Duty and possibly opening a new trend in the video game industry.
Games that bring innovation are tough to find these days so I really recommend you give it a try.
Commentary by FRIGGIN SeaNanners!
(the title of this video is an inside joke of nanners or some sort as the game is not called Flashlight: Tango Town)