A site that should be of interest to all US readers (and many others) is glassbooth.org.
A non-partisan site, it aims to give you an insight into how the views of the Presidential contenders align with your own views.
First it asks you to assign points to issues that you're most concerned about, then it asks you a series of questions about those issues. Based on your responses, it tells you which contenders align most closely with your beliefs and - importantly - provides references and links to back up that assessment.
In case you're interested, the winning candidate for me was Bill Richardson (Democrat from New Mexico), followed closely by Barack Obama and Hillary Clinton. On environment and energy issues, Richardson was well in front (seems he's more of a greenie than I am), followed by Clinton.
More about glassbooth and some other handy election resources can be found in this Wired article.