I love biking because it is a great form of transportation and exercise. In both situations, riding clipless pedals really pays off. The term "clipless pedals" is confusing so it helps to know that as biking evolved, so did pedals. First there were basic pedals (like many of us had on our bikes when we were kids), then came pedals with toe clips (or baskets) to help the foot stay "put" on the pedal, now there are "clipless pedals."
Clipless pedals are a two-part system consisting of shoes that lock into pedals. Cycling shoes have a "cleat" mounted to their sole that literally snaps into a receptacle on the pedal, allowing you to quickly snap into the pedal. To release the connection, you just twist your ankles outward to free your feet. Having your feet attached to pedals takes some getting used to and you might take a few spills before always remembering your feet are clipped into the pedal, but the rewards are large. The primary benefit of using clipless pedals is they aid in efficiently transferring your leg power through pedals, to the gears, and then to your wheels. They help you become one with your machine. Your legs and feet tire less quickly and you can ride like the wind (well hopefully).
The only real downside is cost. Unlike running, which really only requires a good pair of shoes (well, there are the barefoot runners), good biking gear can be costly. Good quality cycling shoes and pedals should last you a long, long time though. Check out Shimano - they make great clipless pedals and cycling shoes for both road bikes and mountain bikes.
If you ride clipless, I'd love to hear how you feel about it. Let me know in the comments section below.