This Google Custom search engine performs a search on websites that have been evaluated for their usefulness in providing data and statistics. Results will open in a new window.
Below are links to other pages that may be of interest to you.
List of National Data Sets with Small-Area Data - This is a list of public datasets compiled by the Urban Institute from federal and nonprofit sources that have data on small areas (point-level, census tracts, zip codes, etc.). The table contains basic information and links to the websites where the data is posted. NOTE: The list is an Excel spreadsheet linked on the page; look for the "Download" link.
University Data Libraries