Well I've played:
Medal Of Honor: Allied Assault - Online for the PC, still a quality first-person shooter and played by many around the globe even though it came out around the year 2000. I myself however don't play it anymore.
Pro Evolution Soccer 6 - Online for the PC. Quality sound, Quality graphics, Quality gameplay, Quality netplay.. Simply quality.
FIFA 07 - Online for the PC. Just as good as PES6, the gameplay and netplay is amazing and it's so easy to play against others around the world.
Call Of Duty 2 - Another supreme first-shooter game, been playing it since around Early December '06. Brilliant atmospheric detail, and overall it's pure awesome.
There were a few other RPGs I used to play years ago like Runescape, Gangsters Paradise, Etc.