Making of America - University of Michigan
"These two institutions are developing a thematically-related digital library documenting American social history from the antebellum period through reconstruction." They have scanned in images of entire books and journals from 1850 to 1900.
Family Tree Searcher - Enter your family data once and this site will search multiple family tree web sites at one time.
Free Public Record Sites - A free gateway to selected searchable local, county, state and federal records Web sites. Included are some important free non-governmental sites.
ProGenealogists: Find out how common a surname is in different parts to the United States. Search uses the census information from 1850, 1880, 1920 and 1990 to track the distribution of surnames across America.