From slashdot:

"Don't have $1500 to drop on a USRP? A Linux kernel developer has discovered that a Realtek digital TV tuner chip has an undocumented mode that turns it into a software-defined radio, with a frequency range of 64-1700MHz. The going rate for one of these USB devices can be as low as US$11. If you're unfamiliar with software-defined radio and have 20 minutes to spare, Balint Seeber has a great video introduction."

The USRP platform has been used as:

An APCO25 compatible Transmitter/Receiver and Decoder^[8]
RFID reader
testing equipment
a cellular GSM base station^[9]
a GPS receiver^[10]
an FM radio receiver^[11]
an FM radio transmitter^[12]
a digital television (ATSC) decoder^[13]
passive radar
synthetic aperture radar
an amateur radio^[14]
a teaching aid^[15]
Digital Audio Broadcasting (DAB/DAB+/DMB) transmitter ^[16]^[17]
Mobile WiMAX receiver with USRP N2x0 ^[1