I think it's a great idea, and the site looks very refined. Just some quick things off the top of my head: I used the inviting big text box on top of the page

I think it's a great idea, and the site looks very refined. Just some quick things off the top of my head: I used the inviting big text box on top of the page right away, only to get a "please register" message. That was disappointing. I believe you should show that box only when it's actually working for a user. Better yet, allow people to create some content before they have to register. Get them invested through a little bit of interaction, then ask them to register. For example, allow them to make a complete top 5 entry first. Then, when the time comes for the "share" part of the process, ask for their account. The account registration process itself is pretty standard, I believe this will hamper your adoption rate. Provide an OpenID, Facebook, Google and/or Twitter login option instead of or in addition to the traditional email-password combo. Having to choose a username is tedious, so I would suggest either getting rid of this (which may not be feasible) or at least putting this part off until the user has opened their account. In a word: make signing up easier, if possible, reduce it to one click.