Here is another quick hacked PogoPlug running ArchLinux as a Apple Airport receiver. You can read more about Pogo and Airplay here.
Total part cost less than $50:
PogoPlug in the discount bin online $15-20.
Cheap USB powered Logitech speakers (regular $30, onsale $12).
Sabrent USB sound card dongle. $7
Extra USB stick for ArchLinux install (free from the recycle bin). You can get away with a 1-2GB USB stick if you are just using Airplay, Airprint, Google ChromePrint.
Of course, I will be using this Pogoplug for other things like Motion USB webcam surveillance. Furthermore, these speakers aren't the greatest but they don't require an extra power outlet. This is just to demonstrate that you can quickly build a very portable, self-contained Airplay sound system with a little bit of geek "elbow grease." I had a few extra Pogos and left-over parts lying around, so I figure why not. The speakers and sound card were extras in the drawer so they were brought back to life. The whole process took less than 20 minutes with an existing image I made for another PogoPlug.
There is only one AC power jack required. The speakers are USB powered by the Pogoplug itself.
I plug the USB sound card in the front so I can adjust volume and do other things more accessible.
Rear is the USB power and OS bootable USB stick.
This thing is so cheap and disposable, I can throw one in the garage or workshop. I continue to be amaze at the ultra cool factor of the pogoplug and its ability to be versatile. If you don't care for Airplay, you can also install a Squeezebox client into one of these just as easily.
Logitech Z120 USB powered speakers: http://www.amazon.com/Logitech-Stereo-Speakers-Powered-980-000524/dp/B004ULOZPQ
Sabrent USB 2.0 USB sound card dongle: