Warhammer Anybody?

[Galt]

Well, Warhammer isn't just an MMO. It's also an RTS.

For medieval Warhammer, it's Battle March.
For the 40k version, that's Dawn of War.

Dawn of War is a total blast, especially since it uses the tabletop's "squads" whereas games such as Command and Conquer and Starcraft use single units. I played DoW for a long time, and now single-unit RTSs just seem really bland to me.