I really like this. I'm actually using it now. Could you not join Facebook Groups and start 'talking' about your website? For example, join some music lovin' group and mention it... or even get in touch with the owners/admins and ask to "affiliate".

Those are just random thoughts, I'm in the same boat as you. :) Good luck!

EDIT: Signed up and everything, but I like to listen to other peoples playlists, however if I'm signed in, I can't find any, because it redirects me to /me and that feature is on the main page ...