All with gameplay videos! Warning! Long post
Age of Conan, This game is for a mature audience. It has both PvP (player vs. player) and PvE (player vs. environment) gameplay where your playing skill really matters. Aiming and dodging is done semi-manually, kinda like Dungeons and Dragons online or a little bit more like Elder Scrolls: Oblivion, but online and more bloody. Conan has a strong community and pretty good community support.
Archlord, A free game with great PvP. You can buy overpowered stuff with real money in this game which means its can get unbalanced for free characters. =(
Aion, Great game with endgame based PvP. By NCsoft. It has large scale castle battles, raids and RvR.
The theme of this game is described as "dreamlike"
Version 2.0 update you can take pictures and send directly to twitter, and some other nifty little features.
City of Heroes, You can make your superhero look like anything you want, the best character customization in any mmorp basically. The heroes engage in pvp against the City of Villains characters (the villain version of this game, see below), while the PvE gameplay is mostly instanced.
In the 2010 Going Rogue update you can change you r alignment from Hero to villain!.
City of Villains, The PvP enemies of City of Heroes.
The two most customizable mmorpg's
Click the link above to get both City of Heroes and city of Villains
Dark Age Of Camelot, DaoC has been out since 2001 and is considered one of the classic mmorpg's. It has PvP (player vs. player), RvR (Realm Vs. Realm) with three realms going head to head;
The Arthurian inspired Albion realm, Norse-Mythology inspired Midgard and Celtic Hibernia.
You can choose between 44 different professions and 18 races. Do you feel like you missed out on the good ol days of MMO?
Bring this old world back! ^ w/30 day pass!! ;)
Dungeons & Dragons Online, Based on the classic that started the whole RPG fanaticism.
Even Gary Gygax (R.I.P), the creator of D&D narrated a few of the dungeons in this game. DDO has Great graphics and finally has some PvP. Mostly instanced dungeons for groups, almost impossible to get very far solo.
If you're into RPG's you should definitely check it out.
EVE Online, A very mature game with deep economy and crafting (manufacturing). You can explore galaxies and extract resources out of everything in this deeply economical driven game. Huge player events and PVP battle
A lot of distance between each object and no avatar except your ship which can take some getting used to for someone who has played a lot of mmo's before.
Pretty big learning curve (maybe 2 or 3 days if you have the whole day)
It's possible to make REAL MONEY through this game.
Image via Wikipedia
Everquest II, Pretty high spec graphics for it's age. Used to be only for high end computers, on lower settings this game can still compete with WoW in graphics.
Is best known for PvE and roleplaying but also has PvP and raids.
Fury, (update: Fury closed down, help Rez Fury)
Full PvP game, there is no grinding in this game, at least not monsters.
You will basically be grinding in the battleground with up to 16 people fighting. (I believe is the max)
The battles are very intense, and you get skills and equips fast. Sandbox based skills and equipment, you can build any type of character and use any skills you want. Personally I think this game can compare with EQII on graphics, and thats pretty good for a free game.
Guild Wars, A game with no subscription fees but you can buy patches. Focuses on end game pvp and of course wars between guilds, you can start with a maxed out level character. Probably the most famous free mmorpg.
(update 2010: Guild Wars 2 Coming out)
Infinity, An asian f2p (free2play) mmorpg with PvP, mission modes and item mall where you can buy special stuff. You can have henchmen (guards) with you in pvp battles or you can fight alone, or with a group.
Last Chaos, Another free game by aeria. It has PvP and pet system.
Also has a item mall, so even though its free you buy items for real cash.
Was very popular in Korea 2003-2005, and still is considered one of the most popular games world wide. PvE and PvP with karma system, pretty good graphics.
Perfect World, Beautiful graphics and large terrains, the monster graphics aren't too great except for the big/famous monstes which are, good, or average. The jumping is weird in this game, you can jump once, do a double jump, do a backflip and then activate flight or just land, but no fighting in the air =(
Rakion, Another free Asian game with pretty good graphics. Lots of PvP gameplay but with a cash shop which makes it unbalanced for free characters.
Rappelz, Free asian mmorpg with pvp, pet system, lots of classes and some new unique mmo features.
RF Online, A free science fiction game with fantasy elements. you begin with human looking characters and end up in robots fighting large PvP battles.
Nice graphics but pretty grind heavy, you can start pvping around lvl 30 which takes you about 3 days to a week.
Ryzom, A nice looking mmo whith nature effects like growing plants, and species of monsters that populate and move around in packs etc. Sandbox based so you can pick and make basically any skill/spell.
Tabula Rasa, FPS (first person shooter) and mmorpg mixed together nearly perfect for the first time.
The reaction time for you aiming is still not perfect and there are no "headshots".
Has both PvP and PvE gameplay.
The Lord of the Rings Online, Official lord of the rings game, great graphics, great PvE gameplay but no PvP yet.
Also based on some other works by Tolkien like Silmarillion and The Hobbit.
Twelve Sky, Free game with cash shop by Aeria. Martial arts rpg based in ancient China. Players belong to one of three armies and fight for holy relics. To make this game they used advanced motion capture techniques, this makes character movement look very realistic.
World of Warcraft, World of warcraft, or WoW has the biggest user community, the amount of content and size of this world is staggering. This world is huge and has so much content, you will never even be able to play all of it.
Xiah, Another good asian free game, based on Asian culture and some European fantasy.
This game features a good PvP and pet system, but has an item mall which means you can buy some items, unbalanced for free characters.
Other games that barely made the list:
2Moons, Free Asian mmorpg, good graphics PvP and PvE gameplay.
Age of Armor, Free mech game game. You control giant transformer-looking robots.
The graphics aren't too high end but the best one of these types of mmorpgs.
The Legend of Ares, Free game with pretty good graphics, but it has items you buy for real money, again it can make it unbalanced for free characters.
World of Kung Fu, Free game based on traditional Chinese culture, history and ancient paintings this game is very deep.
Most of the virtual world is inhabited by monsters, and only cities are a safe.
Too bad it has an item mall which means free characters will be a bit weaker than those who pay for special items, but still, you can play for free
Zu Online, Zu is a 3d mmorpg based on a Chinese legendary Kung-Fu novel. Cartoonish type of graphics that you either love or hate.
Guilds can compete for mansions. There is also flight and a pet system.