If you could solve the problems of 1) users reposting the popular links from other social sites (without attribution), 2) spam bots, or 3) a ruling clique from

If you could solve the problems of 1) users reposting the popular links from other social sites (without attribution), 2) spam bots, or 3) a ruling clique from taking over the front page, then you could compete with Digg and probably beat them.