Serious things or fun things?
Serious you could probably go up to Oxnard and have a tour of the Haas factory.
Fun there are Disneyland and Universal World of course. Also an automobile museum, Petersens (I think??). Lots of other touristy stuff as well.
A groovy place to eat if you are into old airplanes is the Proud Bird restaurant near the airport; a couple of years ago before Westec I hosted a dinner with a bunch of CNCzone guys there.