rechargeable rear light
We reviewed Light and Motion's Vis 180 a couple of years ago and liked it. Since then, it has shed some weight, gained even more lumens and still costs a lot.
The Vis 180 is a (micro)USB rechargeable rear light that is seriously bright, and is visible through 180 degrees. It achieves this through two dedicated amber LEDs pointed to the sides, as well as obviously the main red rear facing light.
Unless that nice Brian Cox has led me astray the mighty Moonshield rear LED should really be called the Sun Shield, seeing as the Moon only reflects light, it doesn't kick it out in great strobing pulses with a disco flash.