Deep Throat was the informant who gave Washington Post reporters Bob Woodward and Carl Bernstein information that helped to expose the Nixon administration's role in the Watergate Scandal.
AllPolitics: Watergate Revisited
CNN and Time's AllPolitics site is a fantastic Watergate resource that includes a glossary, overviews, analysis, transcripts, and audio files from the event.
GOP Security Aide Among 5 Arrested in Bugging Affair
The original Washington Post article announcing the connection between the Watergate burglary and the Republican Party.
The Tapes Online
Listen to the actual tapes that caught Nixon in the act.
Washington Post: Watergate 25
Washington Post reporters Carl Bernstein and Bob Woodward broke the Watergate story. This site provides a plethora of information, including a timeline and bios of the key players.
A very nice timeline of the Watergate affair.
Wikipedia: Overview of Watergate
A wonderful, encyclopedic overview of the Watergate scandal.