I would take a look at BallHype.com. It seems like it's well-designed and well-executed, but hasn't taken off just yet. It would be good to understand what happened - whether they were too broad in focus, or whether there is something about the digg model that doesn't quite resonate for sports fans. As a side note, I would not require registration to vote, and I would not require a valid email address. It don't feel like I should have to send you my email address to say that an article is good or bad.