AO-73 (FUNcube-1) is a very nice cubesat from AMSAT-UK and its partners. If you have not worked it yet, you are missing out. It’s very easy to hear and does not take but a minuscule amount of power to uplink into it’s transponder.
On March 3, I completed my 73rd QSO with a unique callsign/station since September 1, 2014. I had worked well over 73 unique callsigns on the bird since it’s inception but the rules stated the contacts must have been made after that date.
See http://amsat-uk.org/funcube/73-on-73-award/page/2/ for a description of the award and the issuance of #1 to Wyatt, AC0RA.