Essex radio amateur George Smart M1GEO has managed to get the ham radio weak-signal software WSPR running on his Raspberry Pi.
stands for Weak Signal Propagation Reporter and is designed for sending
and receiving low-power transmissions to test propagation paths on the
MF and HF bands.
Details of how George M1GEO managed to get WSPR working on the Raspberry Pi computer board are on his website - http://www.george-smart.co.uk/wiki/RaspberryPi_WSPR