Thomas Jefferson:
America's Library: This site has stories regarding Thomas Jefferson
Monticello: A brief biography of Thomas Jefferson
White House Presidential History: Biographical information of Thomas Jefferson
The American Presidency: A great resource of information about Thomas Jefferson
Signers of the Declaration of Independence: Another great resource with biographical information

George Washington:
Mount Vernon Educational Resources: A brief biography of George Washington
America's Library: This site has stories regarding George Washington
White House Presidential History: Biographical information of George Washington
Learning about George Washington: Five slides with information on the life and times of George Washington
Rediscovering George Washington: Extensive information on George Washington

Benjamin Franklin:
The World of Benjamin Franklin: Brief information regarding his life
The Electric Benjamin Franklin: Multiple resources of information, pictures, timelines, biographies, etc.
World Almanac for Kids: A variety of information on Benjamin Franklin
Hero History: More biographical information of Benjamin Franklin
Ben's Guide to U.S. Government: A great children's resource for information on Benjamin Franklin

John Adams:
Presidents of the White House: A biography of John Adams
World Almanac for Kids: Biographical information on John Adams
The American Presidency: Biographical information on John Adams
Signers of the Declaration of Independence: Another great resource with information regarding John Adams