MMOS: War Thunder, Star Conflict, Robocraft
MMORPGs: Champions of Regnum (its super grindy though), Spiral Knights, Albion Online (in beta)

ones that work great using wine: Neverwinter Online, Champions Online, Star Trek Online, Fallen Earth, Everquest 2, Runes of Magic etc.

Quoting: XpanderMMOS: War Thunder, Star Conflict, Robocraft
MMORPGs: Champions of Regnum (its super grindy though), Spiral Knights, Albion Online (in beta)

ones that work great using wine: Neverwinter Online, Champions Online, Star Trek Online, Fallen Earth, Everquest 2, Runes of Magic etc.

i have yet to get star trek online to work properly if at all

Old, but in case you are still interested.

Upcoming indie MMORPG from the creator of Ultima Online: Shroud of the Avatar - still alpha but pretty good.

Old and pure gold total sandbox MMORPG with a great european community: Ryzom - this game is still alive and kicking, I've played it on and off for many years...

Standard MMORPG with native client but pretty crowded and fun too: Eldevin - I gave up this one after a while because of Ryzom.

Shroud of the Avatar requires an initial purchase, so it's not free to play. I think it's going to be worth it though. No monthly fees, just paying for content.

Also still in alpha, and a real free-to-play -- Stash: No Loot Left Behind http://frogdice.com/stash/
That one is more inspired by RPG board games than in the style of typical MMORPGs, and also has a bunch of developers that love to do role-playing and hang out in the game with players (like IMMs in old fashioned muds, which is their background).

Hey, I didn't know about Stash, thanks!

I also forgot Istaria - www.istaria.com.
Is pretty fun and complex but the population is somewhat low. Crafting is deep and awesome and Istaria has playable dragons, which are actually fun.

I guess the better looking one is Ryzom, as it will soon release some more content and will be available through Steam, which will bring even more new players.