Great web site: www.fivethirtyeight.com

Here's the best web site I've seen with data from each states, not just on the Presidential race either (Senate races, etc.): www.fivethirtyeight.com.  From a friend:

If you haven’t visited www.fivethrityeight.com I highly recommend it. I find it a much more insightful summary of the current polls and frequently includes detailed discussions of various methodologies and their biases. I suspect you’ve heard of it but if not it’s worth a look.