Google Analytics – Web analytics and reporting.
Qualaroo – Behavior insight surveys for better A/B testing.
SurveyMonkey – Free online survey software and questionnaire tool.
App Annie – Mobile app ranking, analytics, market intelligence.
Kimono – Turn websites into structured APIs from your browser in seconds.
Import.io – Web data platform and free web-scraping tool.
UNData – A statistical database of all UN data.
Pew Research – Public opinion polls, demographic research, media studies, etc.
The Data Hub – Powered by CKAN, currently lists more than 3,000 open datasets.
Academic Studies/White Papers
Google Scholar – A wide array of information, including articles, theses, books, abstracts, white papers, court opinions,etc.
Google Finance – Real-time stock market data.
Google Public Data Explorer – Large datasets on economic development worldwide.
The CIA World Factbook – Global information on history, people, government, economy, geography, communications, transportation, military, etc.
U.S. Census Bureau – Demographics, geographic information, and education for U.S. population.
Data.gov – An open data source for U.S. government data.
SocialMention – Real-time social data.
Google Trends – Search data and trends.
Topsy – Social trends and tweet history.
Healthdata.gov – Data on Medicaid, Medicare, clincial studies, treatments, etc.
CDC.gov – Public health data from the Centers for Disease Control & Prevention.
Amazon Public Data Sets – A centralized repository of public data sets that can be seamlessly integrated into AWS cloud-based applications.
Programmable Web – APIs, mashups, and the web as platform.
Datacatalogs.org – A list of open data portals.
Wikipedia’s Open Data page – A comprehensive list of open government data.
r/datasets – A subreddit of datasets for data mining, analytics, and knowledge discovery.
Quora – Ongoing discussion of “Where can I find large datasets open to the public?”