For SoCal WRX drivers... just discovered this EXCELLENT canyon run over the weekend. I just passed the first 1000 break-in miles on my '04 WRX Wagon, so I took it up PCH to see what it could do - dad's a local cop in Malibu, so maybe I won't get a ticket!
Travelling north on PCH past Malibu, a few miles past Leo Carillo State Beach, look to your right for a road marked Deer Creek Road. This two-lane paved road makes an extremely steep climb to the mountain ridge (amazing views!), then turns into a single paved road that snakes and twists for about six miles through the Santa Monica Mountains! There's some excellent hairpins, s-turns, and a few hills that will get you some air (just watch that landing!) The road spits you back out on PCH, a few miles south, so you can go back and do it all over again.
Obviously, use your head and try not to kill anyone (yourself included.) There are a few randomly scattered "Manson Shack" hippy dwellings back there and a few nice homes, so people do live there. But there are plenty of spots that give you a clear look ahead so you can open it up without eating it on a blind turn.
Have fun! Anyone know any other good spots like this in SoCal?