Motorsport Forums  
   Discussion of every form of racing.
   http://www.motorsportforums.com/

10 Tenths Motorsport  
   Discussion forum on all aspects of motorsport from F1, Touring cars, Bikes, Kart to National and club racing.
   http://www.ten-tenths.com/forum/

InTheZone Racing Forums  
   Includes forums for NASCAR, F1, IndyCar, CART, and off road dirt.
   http://invisionfree.com/forums/InTheZone_Racing/

Racing Message Boards  
   Includes discussions on sprints, stock cars, midgets, enduros, karts, dwarfs, vintage racing and drag racing.
   http://www.4m.net/

Speed Society  
   Focused primarily on racing topics such as drag, autocross, and road racing. Also covered are shows, automotive trends and the automotive aftermarket. Includes forums for general topics, current events, and news as well.
   http://speed-society.com/forum/phpBB2/portal.php