Links

This guy has a personal blog that just happens to be the best hiking website in Southern California. He posts detailed trip reports, maps, topos and trail ratings for every hike you can name in the LA area. I love that his site is completely ad free.
http://nobodyhikesinla.com/

Almost everyone in Southern California who hikes already knows about Dan's Hiking page. His website may look like it's straight out of 1995, but he spent years compiling a list of amazing hikes in Southern California and his directions and trail notes are always spot-on. http://www.simpsoncity.com/hiking/

 This is a directory of Hot Springs in Southern California. This map lists several that are located on private property, so tread carefully. http://hotspringsdirectory.com/usa/ca/map_ca_all.html

 World of Waterfalls is the most comprehensive list of the waterfalls in California. http://www.world-of-waterfalls.com/california.html

If you want to go camping in a state park in California, you're probably going to need a permit from the California Parks Department. You can reserve a spot at most campgrounds online. Always book several months in advance , because the parks in California are notoriously busy. http://www.parks.ca.gov/

http://www.caopenspace.org/index.html is a blog with descriptions of hikes broken down by category. You can search for beach hikes, island hikes, desert hikes, lakes, creeks, wetlands, forests and urban nature hikes.

Brian and Ashley's Hiking blog has been around since 2007. They have a cool Google map to let you search for hikes by geographic location here http://abhiking.blogspot.com/p/find-hike-near-you.html

Hiker Hell  hasn't been updated since Christmas of 2012, but that doesn't mean it's any less awesome. This website is pretty much a collection of gruesome stories of hiking injuries, missteps, and fatal ends. Maybe you'll learn from someone else's mistake?