First and most importantly, FiveThirtyEight is a great site if you’re into opinion polls. The guy running it does a lot of number crunching based on published polls (and makes nice illustrations), and in addition he writes interesting blog postings.
In addition (and linked to from 5:38), Electoral-vote.com has nice maps updated on a daily basis.
Finally, and on a more light-hearted note, The Economist’s Global Electoral College is asking everybody on this planet to vote, and the result at the moment is 9120 electoral college votes for Obama, and 158 for McCain.
Only Iraq is strongly in favour of the latter – could that be because most people accessing the internet from Iraq are American soldiers…?