This is not an exhaustive list - just a way to help you get started! Feel free to use data sets from other sources if you find something of interest to you.
ICPSR: Includes data from many sources and on many subjects. It's a great place to start your search!
Baltimore Longitudinal Study of Aging
Bureau of Justice Statistics, Surveys
Bureau of Labor Statistics, Surveys
Center for Disease Control & Prevention, Disability & Health Data Sets
Center for Disease Control & Prevention (CDC), General Surveys
Health & Retirement Study
Medical Expenditure Panel Survey
National Center for Education Statistics: Surveys & Programs
National Center for Health Statistics
National Data Archive on Child Abuse and Neglect
National Database for Autism Research
National Longitudinal Study of Adolescent to Adult Health
National Longitudinal Transition Study 2
National Survey of Children with Special Health Care Needs
National Survey of Families & Households
National Survey on Drug Use & Health
Panel Study of Income Dynamics
US Census, Survey and Programs
This work is licensed under a Creative Commons Attribution-NonCommercial 2.0 Generic License.