Im in Fountain Valley. Well, depends on what you like to do...
I play pool at Danny K's in Orange or at Games Plus in Costa Mesa all the time. Danny K's is a sports bar, but Games Plus is a cool little video game mecca/pool hall/hang out for younger peeps. Its off of the 55 fwy and 19th street.
As far as other hang outs i frequent, Main Street in Huntington Beach is a norm for me- good to hang out with friends and look for chicks (or guys?!?!?!). Laguna Beach Main Beach area on PCH - kind of the same as HB Main St. Otherwise I can usually be found at the Block in Orange. Im either at the movies there or at Alcatraz brewing Company watching sports or having a Large House Red and Bread Bowl of Clam Chowder.
Places for car people to hang out... well, I think its the first Saturday or Sunday of every month, there is a Meet at the Huntington Beach Mall off of Edinger and Beach Blvd. Sometimes its a reallllly good turnout - 30-50 people. There used to be a hang out in Fullerton every Tuesday night on the corner of Harbor and Imperial Hwy at the mexican food place. Also every Sunday Night at the Coffee Shack in Placentia on the corner of Rose and Imperial. I dont know if those two kick backs happen anymore though.
Im pretty much a beach bum though... especially in Laguna where I surf.
Hope this helps.