From the rtl-sdr.com blog: links to a 12 minute video, and a longer 40 minute version, by Balint Seeber showing some of what is available in the VHF and UHF bands using a computer and a software defined radio receiver.
While the videos are from a company that produce high-end SDRs, most
of what is shown can be done with a $20 RTL SDR USB stick and freely
If you are interested in playing with one of these, make sure you get one
that has the R820T tuner chip which can receive from 24 - 1766 MHz. These
will do FM, AM, Broadcast (wide) FM, LSB, USB. You will need some
adapters to hook it up to a better antenna.
Good sources are: NooElec and Adafruit: NooElec also sells through Amazon.
Adafruit is a great source for all sorts of do-it-yourself electronics.
If you are looking to save a few bucks, you can get these from china direct
sites like Deal Extreme, but it will take a few weeks to get to you.