Best Places: Provides detailed reports by zip code, including housing, crime, climate, cost of living and education.
Great Schools: Provides detailed information on schools. Compare elementary, middle and high schools within a school district based on test scores, teacher to student ratio and ratings from parents.
Salary.com: Provides cost of living comparisons between metro areas and salary estimates for different careers.
BankRate: An interesting cost of living comparison tool showing the specific cost differences of a selection of common expenses.