Alexandru Csete, amateur radio operator OZ9AEC, has developed this spectrum analyzer running on a Beaglebone dev board. He calls the project the rtlizer, designed to be a simple real-time spectrum analyzer that uses an RTL2832U DVB-T receiver (RTL-SDR USB stick) and runs on a Beaglebone, or any other device with librtlsdr and Gtk+ installed.
You can find more details including a link to the rtlizer project code at Csete’s OZ9AEC website.