I have one of these at the office:
Logitech Squeezebox
We have a regular one that plugs into our overhead speakers. The duet is a little cooler since it has a wifi remote, but since someone is always sitting by a computer here it's not so important.
We have an airfoil setup at one of the Boss's houses, and while it's cool, it's a little awkward to open a browser hijacked for it and go play music vs. just grabbing a remote and hitting play like the Squeezebox.