Pacific Electric Railway Tours.  Eight tours with simple maps, informative text, and historical photos.  The Pacific Electric system was an extensive interurban rail system that served most Southern California for the first half of the twentieth century.  Some tours may be slow to load.  By Tom Wetzel.  [ccr]
http://www.uncanny.net/~wetzel/pery.htm

Los Angeles Gang Territories.  Maps of African American gangs in LA for several time periods, by Alejandro Alonso of USC.  [ccr]
http://www.streetgangs.com/maps/

History of Pasadena. A short history by the City of Pasadena. Text, and a few photos. [ccr]
http://www.ci.pasadena.ca.us/History/default.asp  

Hollywood Studio Tour.  A tour with photos and nice descriptions of studios located in Hollywood, Burbank, Universal City, and Culver City.  Created by Grace Market Research.   [ccr] 
http://www.gmrnet.com/studio.html 

Public Art.  From USC Libraries this site features photos from downtown and a number of other parts of LA.  Created by Ruth Wallach of USC.  [ccr]
http://www.publicartinla.com

Los Angeles River.  Tour the entire reach of this urban river via photos and descriptions.  Includes a map.  [ccr]
http://www.lalc.k12.ca.us/target/units/river/tour/index.html

San Fernando Valley.  History and lore of this classic American "suburb" within the City of Los Angeles.  Includes a photo gallery and timeline.  [ccr]
http://www.americassuburb.com/home.html

L. A. Nocturne Postcards.   Historic images, with little text, organized by topic and place.  Places include downtown, Olvera Street, Mount Washington, and Griffith Park. [ccr]
http://www.nocturne.com/rack/

Los Angeles in the 1900s.    Nice collection  of maps, images, and descriptions of Los Angeles 100 years ago.  Indexed by topic and year.  Includes a timeline that ranges from 1900 to 1909.  By George Garriques.   [ccr]
http://www.ulwaf.com/LA-1900s/index04.html#1904

Digital Atlases, Searchable Digital Archives, and Other Sites Useful for Exploring Places:

USC Digital Archives.  Search thousands of images from Southern California and elsewhere.   Contains images from several collections, including the Automobile Club of Southern California, the California Historical Society, and the Korean American Archives.  Created by the USC Libraries. [ccr]
http://digarc.usc.edu/search/controller/index.htm 

Los Angeles Mapped.   An interesting collection of historical maps from the Geography and Map Division of the Library of Congress.  The collection includes a 1639 map showing Baja California as an island, some 19th and early 20th century panoramic maps, early 20th century transit maps, and some specific themed maps such as Ragsdale's Movie Guide Map and Bullock's Department Store Tea Room Mat. This project is funded by the Ira and Leonore Gershwin Trust. [ccr]
http://www.loc.gov/exhibits/lamapped/

Los Angeles: Past, Present and Future. From USC library. Extensive searchable photo archives and links to many LA sites.  The project was started in 1996 by the late Dennis Thomison, a reference librarian at the University of Southern California, and continued by Eileen Flick, Linda McCann, and Ruth Wallach in his honor. [ccr]
http://www.usc.edu/libraries/archives/la/