Contains over 100,000 documents including major official documents and links in a single searchable database. Probably the most important website for doing current research on the presidency
Miller Center, University of Virginia, U.S. Presidents
On each president’s page, you'lll f i n d biographical information, speeches, essays, related videos, interviews, and other Miller Center resources. The Miller Center has all the Secret White House Tapes, from FDR through Nixon, many of which are transcribed. Interviews with the Administration contains transcripts and recordings of in-depth interviews with hundreds of top officials from each of these administrations.
Library of Congress, Presidents of the United States: Resource Guides--a separate guide for each president
The digital collections of the Library of Congress contain a large selection of primary source materials associated with the presidents of the United States, including manuscripts, letters, broadsides, government documents, prints, photographs, sheet music, sound recordings, and films. Furthermore, the Manuscript Division holds the papers of twenty-three presidents from George Washington to Calvin Coolidge. The presidential resource guides compile digital materials that are available throughout the Library’s Web site. In addition, each resource guide provides links to external Web sites and a bibliography containing selected works for both a general audience and younger readers. This site will be updated on a regular basis.