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.
US Government Agencies
Domestic Data Archives
International Data Archives
Comparative Study of Electoral Systems - The CSES is a collaborative program of research among election study teams from around the world. Participating countries and provinces include a common module of survey questions in their post-election studies.