Conquer Online
Corum Online
Counter Strike
Diablo I, II
Deicide Online
Dofus
El Kardian
Eudemons Online
Faringroth
Ferentus
Fiesta Online
Fly For Fun
Gate To Heaven
Guild Wars (beta)
Gunbound
Illutia
Lunia
Maplestory
Monster and Me
MU Online
Myth War Online
Pirate King Online (beta)
RAN Online
ROSE Online (beta)
[Scions of Fate - (L.41 Blood Seeker)(L.22 Mage Healer)(L.15 FS Healer)(L.21 Spearman)(L.19 Bladesman)]
Seyken
Spell Casters
Star Craft I, BW
Supreme Destiny
Terra World Online
The Mana World
Trickster Online
Warcraft3 mostly DotA
Water Margin Online
And of course... Ragnarok Online :
official internationalRO(beta), official chineseRO(lvl99 sin~!), avalancheRO, ayumiRO, cakeRO, euphRO, infurnoRO, levithanRO, lyaeRO, mobRO, resurrectionRO, xrdRO and alot more - ^___^UU

Those are just MMO's I've played, there's still tonnes of console: Famicon NES SNES N64 NGC Wii PS1 PS2 PS3 Sega Genesis Dreamcast and hand-helds... GB GBC GBA NDS