Keep those lug nuts on your car!
Most people pay no attention to their lug nuts, but making sure all of them are there and tightened properly is important to you safety. Here is good advice and a video from AutoRepair.com:
You should check the tightness of the lug bolts on all four wheels on a regular basis. If you have had any work done on the car, be sure to double check after 10 or 20 miles. Properly checking them will make your car safe.