http://www.fileplanet.com/promotions/warhammeronline/
Not "open" in the traditional sense, as you'll need to buy a FilePlanet subscription before being eligible. I hope you can afford six dollars, guys.
I never played tabletop games and until someone informed me of what Warhammer was I thought "RTS" when someone mentioned it, but this game actually has caught my attention and interest recently.
Admittedly, after they cut all the content out, the coolest thing is probably how you can level up entirely through PvP. But that's actually really great, and I've never seen an MMO do that and have no idea why.
You can also decorate yourself with COMBAT TROPHIES, like the heads of your fallen enemies.