It looks nice. I can easily see how useful it is. Seeing the sample page was much more informative to me than your landing page though. I would try to integrate the two and show off more of your product on the front page.

Why do you require the Mac app? You should offer both read+write access on the web, with the client app just being an optional bonus. Eliminating that requirement would solve a huge chunk of your marketing problems and open the tool up to many more users.

Nice name change, by the way. :P