Scanning radio waves is fairly cool in the first place. Most people really don't have a clue what's going on and it's fascinating. There's an plethora of various services and devices in this area of spectrum.

http://www.ntia.doc.gov/page/2011/united-states-frequency-al...

Some uses I would consider besides general scanning and exploration would be: amateur radio (multiple bands), NOAA weather stations and satellites, various aviation services, device monitoring and prototype assistance, etc....