ANES produces survey data on voting, public opinion, and political participation. Users can download data or use online analysis tools. The site also includes links to the ANES Guide to Public Opinion and Electoral Behavior (http://www.electionstudies.org/nesguide/nesguide.htm) with prepared tables on selected subjects.
This survey is designed to measure changes in U.S. social characteristics and attitudes. The site contains raw data which can be browsed and downloaded as well as the codebook. GSS data can also be obtained from ICPSR. The GSS has been conducted almost annually since 1972.
The Center conducts national surveys about public attitudes toward the press, politics, and public policy issues. The site contains both raw data, which can be downloaded, as well as commentary and summaries of findings. The newer data sets are in SPSS, and the older data is in ASCII text using a fixed format; Pew strongly recommends that only experienced analysts download these files.
This site contains a comprehensive collection of public opinion surveys, primarily from the U.S. but also from over 50 other countries. K-State is not a Roper Center member so downloading data sets is not free. There is limited free access to the iPOLL databank to locate datasets on particular topics, but users must register. This site also contains extensive links to other data archives.
This site from the Minnesota Population Center contains microdata from the U.S. National Health Interview Survey. Users must register (free). The user selects desired variables and years, and the site extracts the customized data and sends an email with download information. Data is in fixed-column ascii format. IHIS also supports SAS, SPSS, and Stata with special syntax files.
Ipsos MORI is a British company performing polling research, primarily in the areas of marketing, advertising, media, loyalty, and public affairs. Their research archive includes both commentary and data in tabular format.