Wireless Sound System

While working late on a presentation while listening to the classical channel from grooveshark, I started to wonder if there is a gadget that either: a) plays music available from a shared folder on a network or b) receives commands remotely from a computer.

This would be pretty cool, it would allow me to control the music of the whole house centrally from my computer. I remember that a digital photo portrait that I had a few years ago had a similar feature -- it could read its pictures from a designated shared folder in a network, using a specialized protocol. So I imagine there is something similar for music.

The "server side commands" would be better though, because then I could do fancy stuff as setting cronjobs from my computer to change the ambience at certain times, etc.

Or maybe I'm playing too much Shadowrun :-)