Gqrx is a software defined radio receiver powered by the GNU Radio SDR framework and the Qt graphical toolkit. Gqrx supports many of the SDR hardware available, including Funcube Dongles, rtl-sdr, HackRF and USRP devices.
gr-scan is a program written in C++, and built upon GNU Radio, rtl-sdr, and the OsmoSDR Source Block. It is intended to scan a range of frequencies and print a list of discovered signals. It should work with any device that works with that block, including Realtek RTL2832U devices.