One of the great things I love about Linux is the power and flexibility. I've always said that Linux is configurable to the n'th degree, and the fact that I can use it for a desktop or for a server is another reason I Linux gets an A+ grade.
Over the past 6 years I've had my eye on an open source game called The Mana World. The Mana World is a role playing-style game set in an ANIME-based world. I played on and off for a number of years and started a blog last year documenting the game.
Now I've set up a server so others can enjoy the game in a more private setting than the main server.
First download the client from http://www.themanaworld.org/. Clients exist for Windows and Linux, the Mac OS/X client is currently broke I believe.
Playing on the main server server.themanaworld.org currently requires registration through the web site, but you can also play through a number of other servers listed on the TMW web site.
To play on my server just change the server setting from server.themanaworld.org to auldsbel.dyndns.org. Special quest for those interested: See if you can find out what Auldsbel refers to ;-)