(FORTUNE Small Business) – Thanks to an innovative Chicago label called Soundies, an extraordinary collection of vintage jazz and pop recordings will soon be available on the Internet--fully indexed and searchable. Soundies owns the digital distribution rights to some 200,000 unreleased tracks from the golden age of American popular music: jazz greats such as Count Basie, Benny Goodman, and Duke Ellington; early country-western from Sons of the Pioneers; pop gems by Doris Day; and much more.

The recordings are all so-called transcription discs, music that was recorded on 16-inch vinyl discs specifically for radio broadcast. In the early days of radio, record labels feared the new broadcast medium (much as today's labels fear Internet file sharing). Most labels initially refused to license their music for radio broadcast because they thought it would cut into sales. So-called transcription services sprang up to fill this gap, hiring musicians to record alternate versions of popular songs.

By this summer, listeners should be able to search the Soundies archive online, according to founder Kevin Parks, 45. Ad agencies already turn to Soundies when they need that perfect 1940s sound for a retro commercial. The company has also licensed music for Hollywood films and released nearly 50 commercial CDs.

One recent gem is The George Barnes Octet, a two-disc set from a forgotten jazz master. Barnes was a classically trained guitarist who drew on influences ranging from Louis Armstrong's New Orleans jazz to the low-down Chicago blues of Big Bill Broonzy. Barnes's "Private Life of a Vulture" wins best-title honors, but every track conjures a lost world of Studebakers, tea dances, and two-tone shoes. --RICHARD MCGILL MURPHY