World Data: Our World in Data
Open Government Data India - Data.gov.in
Census data: US Census data
Open data concept read more at Wikipedia
Kaggle: Data Science
ProPublica: Wide variety of data available for purchase. Some of the data include Medicare-related data.
Bioinformatics and Science Data:
Reactome.org - open-source, open access, manually curated and peer-reviewed pathway database. Reactome relates human genes, proteins and other biomolecules to the biological pathways and processes in which they participate.
Imngs.com - Integrated Integrated Microbial Next Generation Sequencing (IMNGS).
HumanCellAtlas: A map of human cells.
Dryad Digital Repository: Dryad is a nonprofit data repository for underlying the international scientific and medical literature.
HealthCare Analytics and Data
C-Path.org - The Critical Path Institute nonprofit organization to develop new evaluation tools and standards for drug therapy trial to help accelerate regulatory qualification and medical product approval and adoption.
Healthdata.org - The Institute for Health Metrics and Evaluation (IHME).
National (Nationwide) Inpatient Sample (NIS) - The NIS is the largest publicly available all-payer inpatient health care database in the United States, yielding national estimates of hospital inpatient stays.
DOPPS.org - Dialysis Outcomes and Practice Patterns Study Program. This site contains dialysis data and can work with external researchers for independent analysis. US and International data available.
National Health and Nutritional Examination Survey (NHANES) III data - ( *findinfoandlink*)
AHD.com - American Hospital Directory - information about US-based hospital including financial data. (has both free and paid options)
Social Media Analytics
Twitter: Gnip - Gnip is Twitter’s enterprise API platform with which you can access a wide range of APIs to access twitter data for analytics. Datasift - includes access for social media data for LinkedIn, twitter and facebook. Shifter - provides search and retrieve access to every undeleted Tweet in the history of Twitter. Discovertext - access to free Twitter Search API data as well as premium Gnip PowerTrack 2.0 Twitter data along with cloud-based software tools to quickly evaluate large amounts of text, survey, and Twitter data. Quandle Twitter datasets - mainly financial and company related, it includes free and premium datasets. Twitter data grants for academic research.