Roper Center for Public Opinion
Roper Center for Public Opinion accesses over 500,000 survey questions since 1935 broken down by percentages for each value.
Pew Research Center
"Nonpartisan "fact tank" that provides information on the issues, attitudes and trends shaping America and the world. It does so by conducting public opinion polling and social science research; by reporting news and analyzing news coverage; and by holding forums and briefings."
World Public Opinion
An international collaborative project whose aim is to give voice to public opinion around the world on international issues.
ICPSR, Inter-University Consortium for Political and Social Research
Established in 1962, ICPSR is the world's largest archive of digital social science data.