I have been into RC cars on and off for over 20 years, mostly bashing but I briefly raced at West Coast RC Raceway in SoCal before it closed. Now you'll find me once in a while at Nor Cal Hobbies.
My RC Cars and tipsRC Scrapyard - Database of Vintage RC Models, a great resource
RCTech Forums - One of the more popular forums for RC users of all kinds but especially racers, with a very active classifieds section.
Petit RC - France's gift to the RC world, setup sheets for nearly every car out there