What to do with a site that accidentally got popular?

4 few years ago a friend and I made www.turntubelist.com to scratch a personal itch. We've never tried to advertise it or push it anywhere but overtime the users slowly climbed from 50 hits a day, to 100, to 150... but then 6 months ago something happened. I dunno what, but it happened from Brazil, and then Japan then kind of everywhere - 6000+ visits a day for weeks. It's settled down now - about 1500 visits a day... but the people who use it have a REALLY long average-time-on-site: 26 minutes, according to Google Analytics.

There's no ads up there at the moment, which would be the obvious thing - but because it's all client-side it would be hard(er) to get relevant ads (like for the songs the user is searching for etc).

Anyhooo.... What would you do with it?