Free MMO's

I know there are a lot of them, but which are actually good?

Rubies Of Eventide, probably the most under-rated, unknown but well developed mmorpg.
Some people find it a little slow but there are a ton of classes and it`s very deep, try it out.

Ragnarok Online is the most fun I've ever had playing a MMORPG. And they have free servers now.

Runes of Magic is shiny and new and free (and not half bad). The most polished, p2p-like MMO that I ever played (free) was Silkroad. It's a huge grind, but it's pretty damn fun and it's got a really interesting economy.

Played Shadowbane for a little bit. didn't seem that bad.

Im getting really into Shin Megami Tensai: Imagine. Then again maybe thats because ive got about 4 friends playing it and more coming.