When building something new, as in there are no exact predecessors, it is important not to fall into the trap of premature design. Focus on the functionality first - pursue solving the problem. Let solving the problem elegantly come a little later.
For example, when Digg was first invented, there weren't any other "social voting" sites. Someone with a bias towards design might have asked, "so is this a blog? Or a forum? Well, we should add threads and categories and all the other good stuff a forum should have." That would have diluted the purpose of Digg, and its message.
Solve the new problem first, then try to smoothen the edges.