Just signed up, couple thoughts:

- I think it is pretty clear what you do, so that is good

- The left right buttons on the homepage weren't working for me

- after signing up its weird to see some red text "You're 33% of the way there...", it makes me think something went wrong.

- its also a little weird that I have to add my e-mail address again to create my first notification, maybe that should be pre-populated with the address I signed up with to save a step when signing up.

- I got 2 e-mails every time (signup, e-mail verification, notification)

But it looks cool, I will give it a try on some of our pages, nice work.