Supreme Court Historical Society: Profiles of justices, historical sketches, documentaries, teaching materials, selected content and a PDF guide: Researching the Court.
SCOTUSblog: Not just a blog! SCOTUS blog also has or links to opinions, oral argument transcripts and audio, and statistical information.
Oyez - U.S. Supreme Court Media: The "authoritative source for all audio recorded in the Court since the installation of a recording system in October 1955," plus information about the court, its opinions, and its justices.
Oyez Justices: Extensive Bio of each justice for all courts through the history of the Supreme Court.
United States Supreme Court Justices: One hundred and twelve Justices have served on the United States Supreme Court, including seventeen Chief Justices.