Your concept is good but I think you are simply going after the wrong niche. Web2.0 guys have bookmarks/tabs and once they fire FF they probably have all tabs open and they can use the google search box on the toolbar. You should apply the same concept to sports for example and create startup page with the hottest sport website and links ...Then go after teenagers and launch the Gossip or Hollywood startup page...Before you know it you will have all these niche communities. That's just my 2 cents.