National Portrait Gallery: Hall of Presidents This provides portraits and brief descriptions of presidents. A neat Quicktime VR virtual tour available. It is part of the Smithsonian Institution's National Portrait Gallery.
From the site:
This virtual tour will allow you to navigate through the National Portrait Gallery's, Hall of Presidents. As you "walk" through the spaces you may select specific portraits for more information and larger images. Portraits can also be selected from the chronological list featured on the right side of the screen. An 800 x 600 screen resolution is strongly recommended.