There has been a lot of talk about unintended acceleration lately. If unintended acceleration occurs it can startle the driver, however it is extremely easy to deal with.
First, put the car in neutral, do not turn the car off yet. By putting the car in neutral and leaving the engine running you will stop the car from accelerating, but you will still have power brakes and power steering.
Secondly, coast to a safe location and bring the vehicle to a stop.
Thirdly, turn the car off, and put the car into park.
Lastly, check for the cause of the unintended acceleration. Is pedal stuck to the floor? Often times a floor mat will catch the pedal and make it stick to the floor. Check under the hood, is there something amiss with the accelerator cable? If everything seems okay, restart the car in park and observe what happens. If the vehicle idles normally, you may be fine to drive it. If the vehicle races, then turn it back off and have it towed to a shop.