Lake Mary, Fla.-based Spectrum Bridge, which is headed by former Motorola (NYSE: MOT) executives, is launching SpecEx.com, which aims to create a secondary trading market for valuable spectrum. The site goes live today with an initial inventory of about $250 million in airwaves, and the company will take a cut of each transaction.

Spectrum Bridge has raised $2 million of seed financing and is in the middle of a second round, reports the WSJ today. Its investors include the Telecommunications Development Fund, which is financed by the federal government and has FCC Chairman Kevin Martin on its board. Initially, spectrum is sold at auction by the FCC, but after that it can often become a very fragmented market, and airwaves can literally go unused. Spectrum Bridge hopes to change that by creating a secondary market where unused licenses can easily be resold. Up until now, some carriers have had teams of lawyers and experts whose sole responsibility is to find unused spectrum and buy it at a bargain. This was Clearwire’s (NSDQ: CLWR) strategy as it compiled enough spectrum to build a nationwide WiMax network.