http://en.wikipedia.org/wiki/Rio_Karma 20GB HD-based, supports OGG and FLAC. IIRC, it's Linux compatible. I'm not 100% sure though. I don't think it's still in production, but it looks like you can still get 'em (according to Froogle).
I've had two of these, and they die rather quickly (something weird going on with the hard disks). Plus, they're EOL'ed, so I don't think you can get much support. Although the Karma is pretty great if it works, I wouldn't actually recommend it (anymore).