I suggest maybe checking out www.mmorpg.com and see some reviews of pretty much every online role playing game available (that is known). Some are popular ones you have to pay for like FFXI, WoW, EQ2, etc. But they also have reviews for a lot of free ones, and even advertisements.

If you do want a somewhat quality free MMORPG, I'd suggest looking at Korean made ones. They seem to be the only ones that are decently made, and also free.