The Historical Society of Delaware has a card index to many biographical items, called the Family Surname File, with approximately 500,000 names. (See the "Genealogy" section.)
Some representative biographical publications or collections are:
Bendler, Bruce A. Colonial Delaware Assemblymen, 1682-1775. Westminster, Maryland: Family Line Publications, 1989. (FHL book 975.1 N2b.) The name, death date, county of residence and date, and often the parents, wife, children, and sources are listed.
Biographical and Genealogical History of the State of Delaware . . . Two Volumes. Chambersburg, Pennsylvania: J.M. Runk & Co., 1899. (FHL film 1000155.) This contains biographies from the 1600s to 1890s.
Turner, Joseph Brown. Genealogical Collection of Delaware Families. Salt Lake City, Utah: Genealogical Society of Utah, 1948. (FHL films 006272-300.) This consists of alphabetical files for about 3,000 families. The Delaware Public Archives has the original films.
The Delaware Public Archives has a Book Catalog Index on 3 x 5 cards which indexes names mentioned in genealogies and local histories. This is by surname and does not contain given names. This is not a complete index to all the surnames. They will search it for you, if you include a large, self-addressed, stamped envelope with your request.
Reverend Joseph Brown Turner Collection: http://archives.delaware.gov/exhibits/document/turner/toc.shtml
Delaware Biographies Project: http://www.rootsweb.com/~debiog/