Historic Sites of Los Angeles Digital archive of Historic Los Angeles by the USC archives, part of their very interesting "Los Angeles Past, Present and Future program.
Los Angeles Public Library's "Electronic Neiborhood" The "California Index" is an outstanding archive of old frequently asked questions (FAQ) that cover everything from who Crenshaw was to the slogans of California cities. Also see the "Photo Collection" which is an archive of thousands of old photographs from all over Los Angeles County.