When I sailed from SF to SD last year I thought there was only a few as well...turns out I was way wrong. I quickly listed many of them in the article below (I think I've posted that here b4) but am working on a much more detailed description of each. If that's of interest to you then I'll make sure you get a copy.

http://www.saygudday.com/2012/09/13/free-california-anchorages/