Health08 is an all-singing, all-dancing website created by the Kaiser Family Foundation to analyze presidential candidate positions on health care policy. For climate change, by contrast, the best I've seen is this Heat Is On comparison chart provided by the League of Conservation Voters. Time for LCV to step up to the competition.
Meanwhile, I've put in a link to my post comparing presidential candidates on climate change in the list of links near the top left of the Backseat Driving website, titled "Pres. candidates and climate change." I'll try to update it when possible.