I'm using slimserver to drive my Rio receiver at this very moment.

I'm running an old version of rioplay on the rio, and just have it pointed to the mp3 stream from the slimserver. The interface on the rio doesn't do much (volume, mute, and stop/play), but at least it plays for long periods without flaking out (something none of the rio-specific clients and servers have been able to do).

I've been thinking of altering one of the clients to at least partially interact with the slimserver. Simple interaction should be, I suspect, easy. Next-track, pause, and play could even be done using only http requests. The display partially works as-is, since slimserver puts the current track and artist information in the mp3 stream (which rioplay displays).

True integration would be more work, but perhaps the fact that the new roku mp3 player uses slimserver and has a bitmapped display means there is now configurable display code...

Slimserver is really nice, though. Easy to set up, easy to use, handles any number of clients each with its own stream, stable.