Vizala is an online database that is completely free and open. It would be the only site on the list that combines economics, market research, demographic, and industry data from many different sources and organizes the data for specific areas of interest. Vizala also provides tools that allow you to customize any view of data with filtering and sorting options. You can then save, share, or export any of those customized views.
A nonpartisan think tank that conducts public opinion polling, demographic research, content analysis and other other data-driven social science research. Their mission is to enrich the public dialogue and support sound decision-making.
Located at Cornell University, the center holds archives of public opinion surveys dating back to the 1930s. To search their holdings, click on the 'Search iPoll' link. This site has video tutorials as well; hover over 'Support', then choose 'Video Tutorials'.