Radio control vehicles are great fun and are becoming increasingly affordable as the technology drops in price. LiPo batteries, brushless motors and low cost accelerometers & gyrometers have made multi-rotor aircraft like quadrotors available to anyone who is interested, which certainly includes me! I have quite a few vehicles now: multiple planes, two larger quadrotors, one FPV quadrotor and some toy quadrotors for safe indoor flight.
For the ground, I have a few cars including a 1/8 Scale Truck and a monster 1/8 nitro HPI Trophy 4.6. They are good fun but I enjoy the freedom of the aerial vehicles which can be flown in many places.