The Statistical Abstract of the United States is a great compilation of national statistics from many sources -- government and private. It also is used as an index, or finding tool, to find the source of the statistics.
The Green Book is the standard reference for social policy and federal entitlement programs. It includes descriptions of the program descriptions and historical data on a wide variety of social and economic topics.
Looking for data about children? Kids Count Data Center from Annie E. Casey provides additional data not covered in Factfinder -- such as rate of substantiated child abuse and number of hours of television watched. You can drill down on some of the indicators to county and city level data.
Demographics of people with and without health insurance coverage is tracked by Census Bureau through three surveys. A national snapshot is available of Income, Poverty and Health Insurance in the United States.
The U.S. Census Bureau provides local, state and national statistics relating to poverty, educational attainment, overcrowded housing, single parent families, grandparents raising grandchildren, etc. Much of the data can be "cross-tabulated" by another variable such as race/ethnicity, gender, immigrant status, language or age. American FactFinder is the main entry point. This isn't as easy to use as it should be -- ask your librarian if you'd like help!