I like the concept, have wanted to do something myself for quite some time (my process only went as far as registering a URL).

I don't like the idea of this as a list that is basically just a webpage though. It needs to be more "integrated", at least as a separate window that can popup to open links in the main browser window.

You'll also need a bookmarklet that allows users to book mark sites (ideally) to both the browser and to browserpop.com at the same time.

Another good idea would be a category class that you could share with certain friends. This way, 3 people working on a project could all add bookmarks to this category or group for the others to see. Or, just for casual social bookmark sharing.