Sorry, I meant to reply earlier, but got distracted by a bug.

Thanks for pointing out the typo! That's probably been kicking around there for awhile now. :-)

Wavo detects a referral by checking for referral tokens in the url's querystring. When you share a song, share a playlist, etc, from within the app itself (with one of the share buttons, for example), Wavo crafts a url with this referral token. When a user follows that url and signs up, that referral is credited to you. Obviously, this doesn't catch everything (if you simply copy the url from the browser bar and share it with a friend, you won't get reach points), but it gets us part of the way there.