2Moons
Talisman Online (awesome little game)
Mythos (if you can get an invite)
Hellgate: London (ultimate grinder if you ask me, but its B2P [and P2P if you want] so eh not everyones cup of tea)
WYD Global
9Dragons
Regnum Online
12Sky
Dungeon Runners (another great F2P/P2P grinder)
