Hey Ben
Continue with your retro Retro Boom Box theme and build something with an SDR dongle. http://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/
It's be really cool if you could select the frequency bands (AM,FM,SW, or Ham even) using the Raspberry PI's input pins and even tune in the station with with a retro style dial. A truly portable radio that doesn't need WiFi...