What are the best free multiplayer online games

I would say guild wars.
You have to buy the game,but the play on the internet is free.
You can find the demo at GuildWars.com free to download.
I personally think that eather Runescape or Jamlegend are the best multiplayer games online. Runescape u can rome free in the game and do anything u can think of doing and it has changed alot over the years and have gotten even better, so I recommend playing Runescape. The other game jam legend is a Guitar Hero game that u can play multiplayer and play by yourself. It has some amazing graphics for a online Guitar Hero game. So PLAY IT!!!!!!!!!!!!!!
There are lots of different free MMOG's. One of the best free online multiplayer games is Runescape, online here -> www.runescape.com. It is free but if you want to pay to be a member you get can get extra things. Another game is www.jamlegend.com. It is one of the best Guitar Hero based games online. Some of the ones for younger people include Club Penguin, www.clubpenguin.com, Moshi Monsters, www.moshimonsters.com and more.