This Bicycle Seatpost LED Tail Light from Lightskin is kind of unique. Most bicycle tail lights are set at the back on the fender. This one has to be installed on the seatpost, right under the seat. So basically, there’ll be a beam of light coming out of your butt. That said, it is a surprisingly hi-tech and versatile system for something as simple as a tail light for a bicycle. It has five bright LEDs, and can be installed on just about any kind and size of seatpost. You can choose operational modes just by pressing the button. It works on two AA batteries that give you 400 hours of light in the three-LED mode, and 50 hours in the five-LED mode. It’s waterproof, and the location makes it a lot harder to damage or steal.