Ontheissues.org is a little bit junky but it has a lot of information on where the candidates stand, well, on the issues. It then graphs them on an interesting spectrum based on where they stand on government intervention in the social and economic spheres.

Social Questions:  Liberals and libertarians agree in choosing the less-government answers, while conservatives and populists agree in choosing the more-restrictive answers.

Economic Questions:  Conservatives and libertarians agree in choosing the less-government answers, while liberals and populists agree in choosing the more-restrictive answers.