EA's Warhammer Online: Age of Reckoning - a subscriber-based MMO - has gone completely free of charge, forever. Provided you don't mind playing the trial version. Forever.
All 24 careers are available, with players free to run around until they reach level 10, at which point their exploits are capped.
That's one hell of a hook; get people in, get them juiced up on levelling, then withhold their supply until the money comes in. It's a tried and tested sales pitch for other forms of addiction, no reason it won't work here.
If you're interested, the download link is below.