Biography.com
A searchable directory of more than 25,000 biographies from the Biography Channel.
http://www.biography.com/

Biographical Directory of the US Congress
Search for information about congresspeople by name, position or state from 1774-present.
http://bioguide.congress.gov/biosearch/biosearch.asp

First Ladies Gallery
Biographical information on president's wives from the book The First Ladies written by Margaret Brown Klapthor and Allida Black.
http://www.whitehouse.gov/history/firstladies/

Lives
A web guide to biographical information on people who have died.
http://amillionlives.com/

PeopleSpot
Search for people, addresses, and phone numbers. Find biographical information and lists that rank people by different categories (for example, FBI Most Wanted, Richest, etc.).
http://www.peoplespot.com/

President's Hall
The official biographical guide from the Whitehouse, it provides biographies from the book The Presidents of the United States of America written by Frank Freidel and Hugh S. Sidey
http://www.whitehouse.gov/history/presidents/