ICPSR is the world's largest repository of social science research data sets. Most data sets are available in Stata, SPSS, R and SAS formats. ICPSR also lists recent publications that utilized the data set in its research. For assistance in acquiring data-sets, contact Carol Hansen Karsch.
"The SIPP is a series of longitudinal studies of U.S. households and individuals that has been conducted by the Census Bureau. Data is collected on income, labor force participation, government program participation and demographic information.
FAOSTAT contains time series and panel data related to hunger, food, food security and agriculture for 245 countries from 1961 to the most recent year. Also available is an agricultural emissions database.
This section within the Census Bureau's site bring together data sources, publications, links to other source, and much more.
You can find the most recent data in several subject areas, including poverty and income, in the American Factfinder and American Community Survey sections of the site. Another useful area is Well-Being.