I know amateur astronomers, astrophotographers in particular, are adding them to their imaging setups with great results. You can run an amateur observatory, telescope and camera from your backyard while you are in your living room.They are incredible little machines.
They are also very useful in HAM radio setups. I have an SMA Software Defined Radio that can be easily controlled to perform all sorts of interesting functions such as tracking local air traffic using their transponders, or just listening to frequencies between 500 kHz to 1.7 GHz FM or AM with numerous options available.