I didn't think I'd ever say this, but this would be a good candidate to have a Facebook app. The logic being that I can go on the website to make predictions, and then show them off to my friends on Facebook.
I second that. I Facebook component to the site would be a great way to get the site out there in front of people, and it would also help with the login issue. It would also be interesting to see that "Your friend, Justin thinks that the Patriots will win the Superbowl in 2009"