The Pew Research Centers make many of their data available for public access and download through its databank.
The Pew Research Center for The People & The Press offers free access (with registration) to its data archive. Datasets are currently available dating back to January 1997. The Center's survey data are released six months after the reports are issued and are posted on the web as quickly as possible.
The Pew Hispanic Center offers free access (with registration) to its datasets dating back to December 2002.
The Pew Global Attitudes Project provides free access to datasets dating back to 2001. Survey data are released after all reporting is completed and are posted on the web as quickly as possible.
The Pew Internet & American Life Project provides free access to datasets dating back to 2000. Survey data are generally released no earlier than six months after the project has issued a report about the survey.
The Pew Research Center's Social & Demographic Trends project offers free access with registration to its data archive. Datasets are currently available dating back to 2005. The Center's survey data are released six months after the reports are issued.
Link(s):
http://pewsocialtrends.org/downloads/
http://www.pewinternet.org/data.asp
http://pewglobal.org/datasets/
http://people-press.org/dataarchive/