These are some data sources and sites that I use currently or find interesting for potential future work.
Local Area Unemployment Statistics
National Vital Statistics System - Natality
National Vital Statistics System - Mortality
Behavioral Risk Factor Surveillance System
Uniform Crime Report
Health and Retirement Study
Integrated Public Use Microdata Series (IPUMS)
Zillow Home Price Index and other metrics
Network of physician referrals in 2011
Racial Dot Map
National Instant Criminal Background Check System.