This looks really interesting, but to be completely honest, I lost all interest once I saw that there was no other option but to sign up with Facebook.

As a developer, I understand the business and UX need for it, but it still manages to turn me away from really interesting services. It looks like you're looking to improve on this pain-point, so I'll definitely check this out later. :)

I'd also love it if the About page was on your own site as well. Linking to the Facebook app page feels like you were a little rushed.