Curious about those sirens around Los Angeles? This person mapped them all and has information about each one as well.
Links
T.M. Schultze Photography
I recently discovered a treasure trove of photography for US 80 and more. T.M. Schultze is based in the San Diego area and has a big interest in old highways, as well as rock art, scenery, and more. He has quite a passion for the art and I strongly recommend checking this site out.
Save California Landmarks
There are many historic locations in California. Many of them are marked with plaques. Over time, these have been stolen or otherwise gone missing. A group, called the California Landmark Foundation, is working toward replacing those markers. They are looking for your help.
Transit Tracker
While not specifically a real-time tracker, this neat website has a clickable map where you can locate transit vehicles, get next stop information (though not time), and a map of the route. It seems more likely a visualization of where things should be if the schedules are followed instead of something to assist passengers. From what I’ve found, it covers the Los Angeles and San Francisco regions in California. Other cities, such as Phoenix, Arizona, are also covered. The site is Swiss, hence the .ch TLD.
Los Angeles History Link
When looking for images of the Pacific Electric Railway or something showing US 99 near downtown Los Angeles, I found this really cool website with a lot of old photos of the Los Angeles area. I recommend a visit! It is called Water and Power Associates.