Statisticians love to play with data. Here are some useful links where you can find publicly available datasets.

Small-medium datasets

The R datasets package

Clustered data 1

Clustered data 2

Mendeley Data

Data in Brief

Some toy data sets

A Handbook of Small Data Sets

Journal of Statistical Education Data Archive

Large data collections

Comprehensive Epidemiologic Data Resource (CEDR)

UCI Machine Learning Repository

National Health and Nutrition Examination Survey

US Birth and Infant Mortality Data

U.S. Government’s Open Data

More coming soon…

Have fun!