Great Debate & Beyond: The History of Televised Presidential Debates. This site is a multimedia examination of American Presidential from 1960 to 2000. It includes video, photographs, and curriculum resources.
The most visible debate covered is the so called "Great Debate." This was the first Television debate between presidential candidates and it featured Kennedy vs. Nixon. Other topics include Televised Debate History 1960-2000, and Television: The Great Equalizer. What is nice of each of these sections is that they are loaded with videos, transcripts, photos, essays, and coverage of "spin" that played out after each debate.
The Curriculum Resources is also nice with lesson plans using the debates for courses in government and politics, history, debate, and communication. All in all, a nice site! I hope information on the 2004 debate goes up soon as well.