What are some good online pc games?

currently playing modern warfare 2 and guild wars (i like mw2 for the action and gwars bcuz its huge and hold my interest) so any games similar or decent customization

i prefer games with free onlineplay no fees

COD 4

Team fortress 2

Battlefield 2

Counter-Strike Source (FPS)

Left 4 Dead 1 and 2 (FPS)

Warcraft III + Frozen Throne (RTS)

League of Legends (Free DotA clone)

Heroes of Newearth (Another DotA clone, requires beta key though but its pretty easy to get)

Battlefield Bad Company 2 coming out soon (FPS)

Modern Warfare 1 (Which I thought was better than the second)

Team Fortress 2 (FPS)

Battlefield 2 (FPS)

Company of Heroes (RTS)

Dawn of War 1 and 2 (RTS)

Garry's mod if your into that sorta stuff

*EDIT* Scrap WoW, didn't see the free stuff. Highly recommend League of Legends then, as its the only thing I said which is actually free :P