TheatreHistory.com
Theatre history.com: Sophocles and His Tragedies
This site provides a complete biography of Sophocles reprinted from a drama history book. Includes his innovations in ancient theater and his achievements as an artist.
Other
Sophocles: The Man and His Plays
In addition to the usual biographical material and links to English translations of his plays, this includes a long discussion of "Oedipus the King," Sophocles' most famous work.