The Universal Receiver

Ettus Research LLC is selling a radio reception USB 2 peripheral which can tune (with the right daughterboard) the radio spectrum from DC to 2.6 GHz. With the right software, you can accomplish any radio (reception) related task. For that software, it relies on GNU Radio, an open source software radio framework. Pretty damn slick for $550! Think of it as a broadband RF-to-digital converter. Runs on Mac OS/Linux/*BSD/windoze, too!