RTL-SDR is a USB dongle that can be used as a computer based radio scanner for receiving live radio signals in your area (no internet required).
Can tune from 500 kHz to 1.7 GHz and has up to 3.2 MHz (2.4 MHz stable) of instantaneous bandwidth.
Great for many applications including general radio scanning, air traffic control, public safety radio, ADSB, AIS, ACARS, trunked radio, P25 digital voice, POCSAG, weather balloons, APRS, NOAA APT weather satellites, radio astronomy, meteor scatter monitoring, DAB, or for use as a low cost pan adapter with a traditional ham