Ryzom is an MMORPG which was opensourced few months ago. Now the game has an official Linux client. The porting work has mostly been done by volunteers from GNU/Linux community and now Winch Gate Properties embraces the new community with a competition around the official release of Ryzom Linux client. There’s free registration for 21 day trial, which is plenty to complete the competition, and the monthly fees aren’t that bad if you want to continue with the official servers after the trial.
Check out The Humble Indie Bundle #2!
The bundle contains 5 indie games, has no DRM and you may pay what you want.
I usually don’t want to promote anything proprietary, but I want to make an exception with this bundle. I strongly favor this kind of marketing strategy.