There's an infinite list of things you could do, for example:

- wireless pentesting of GPS, RFID, NFC, garage doors, car remotes, etc.

- Receive NOAA satellite weather imagery

- Track airplanes using ASD-B

- Amateur radio voice/morse code/digital modes

- Run a GSM base station using OpenBTS

- Capture every FM radio broadcast in your area, simultaneously

- Transmit a DVB or ATSC stream to your TV