Implement Song Bounties
I think usership would skyrocket if people could place bounties on songs they sorely wanted identified. That is to say, whoever identifies the song will recieve a reward for doing so. Watzatsong could take 12.5% of the bounty price, or 1/8th. So if I put up a 4 dollar bounty, then I'd also pay watzat 50 cents. There are lots of people who listen to obscure music that wouldn't mind some quick cash.
Also give people the opportunity to follow songs that they liked, but couldn't identify, so they can see the answer. That way it provides a means of getting quick cash while also introducing the person to new, obscure music.