A number of big name presidents get first round byes -- the rest are seeded into different brackets.
Simple. Cheesy. Fun.
Click over to: http://www.allpresidents.org Round 1 started today, February 20th and continues through Sunday. After you vote, you can see the current scores.
They're of course playing it up here in West Michigan, so the early voting tends to reflect some of the political flavor here. But anyone on the Internet can vote.