In case anyone is interested, San Diego County Parks & Recreation has an on-line reservation system. What is neat about this system is a breakdown of camping parks by park within the county and the ability to reserve "on-line" up to a year in advance.You can use your credit card on this secure site. This site has a calendar so you can view what parks have vacancies on what days. Once you get to the park of choice, you will notice the "red" sites are reserved for any given day and the green ones are not. "Click" on a green one and infomation pops up giving you the site demensions and a photo of the site itself. Also, once your reservation is made, you are sent a confimation to your e-mail within a few minutes. You can print this out & take it with you when checking in in case your "hard copy" they send via regular mail does not make it in time. We use this all the time and it really works. Maybe I should have posted this in "Campgrounds-Federal, State & Provincial".
http://www.co.san-diego.ca.us/parks/online.html