I spent the weekend sucked into Vendetta Online, a MM-Space Sim. It falls somewhere between EVE-Online and the classic single player game, Elite. You can sign up for a free trial (8 hours of gameplay) and after that it costs $10/month. There’re clients for Windows, Mac OS X and Linus. I’ve been playing it under Linux and it works flawlessly.
The developers are really active and take player comments seriously. I’m not sure its quite worth $10/month yet, but I may sign up just to help support them, since the game has a lot of potential and I want to see them make it.