Public opinion data

Catalist is a database of US voter registration and demographic data. The database also integrates data from the US Census. 

The i360 database is a resource of aggregated U.S. voter registration and election data along with other demographic and survey data points.  

Sysomos is a social media analytics platform with aggregated data from: Twitter, Facebook, Instagram, Pinterest, Tumblr, LexisNexis, and more. Based in Toronto, Sysomos offers global coverage of social media data.

Crimson Hexagon is a social media analytics service, based in Boston, MA, that indexes social media posts from a wide range of global sources,and maintains an online repository of social media data and a platform for social media analytics. The data library provides posts from content providers including: Twitter, Tumblr, Google Plus, Blogs, Forums, Facebook, Instagram Hashtags, Reviews, News, Comments, and YouTube. 

Eurobarometer is a series of public opinion surveys conducted by the European Commission. The surveys address a variety of topical issues relating to the European Union throughout the member states. Survey results are published by the European Commission. 

The Association of Religion Data Archives is a collection of surveys, polls, and other data on American and International religious topics submitted by researchers and made available online by the ARDA.