I try to keep this site focused on interesting technology issues, but http://www.electoral-vote.com/ is just too interesting and useful at the moment (at least to people in the US), so I wanted to call it out.
http://www.electoral-vote.com/ takes daily polling data from around the nation and feeds it into a US map showing how the electoral votes would fall out were the polls to correspond exactly to votes.
According to the site, two days ago neither candidate had the required 270 electoral votes. Subsequent to the most recent debate Kerry has 280 electoral votes, so the debates certainly have an impact on people's polling responses (and presumably voting responses come November).
Also, here's a graph over time showing the total electoral votes for each candidate.