SpiralFrog.com, a site that looks to transition the music industry to an ad-supported model, launched today after several years of tumultuous beta testing.

Originally billed as an iTunes-competitor, the site struggled to get off the ground, with problems ranging from an executive shakeup to a cash crisis. But at long last SpiralFrog has opened with about 800,000 songs and 3,500 music videos.

Most of the site's content comes from Vivendi SA's Universal Music Group, the only major label to cut a deal with SpiralFrog.

Users will be able to download music from the site for free in exchange for watching 90 seconds of ads before each track and answering monthly questions about their buying habits.

SpiralFrog has said it will stick to display ads and other less intrusive ad units.