This is a very fragile (but interesting!) idea. I would focus hard on finding ways to line up a steady stream of interesting (hopefully viral) content... the fragility of the concept all hinges on that. You may literally want to create some pages yourself, or solicit freebies from clever folks, or even
pay or otherwise encourage some great content.
As a user/visitor, I'm going to need a compelling reason to visit your site everyday, and "what would happen if the banner ad and the site content switched roles" isn't very enticing. Now, a cool piece of interactive art one day, a great 24-hour deal the next, followed by a free album/song download from a few artists, with a clever game the next day... these are some of the kinds of things that may give you traction. It's got to be "wow this site has cool stuff everyday" not "let's see what ad is up there today".
It's a chicken/egg horse/cart problem, but you're probably putting the cart before the horse if you're thinking monetization and advertising right away. I'd think of it more like "send in your cool stuff and we'll pick the best to display for 24 hours" and see if that works.
Again, great idea, but you have to prime the pump!
