Originally Posted by DrPete
If you have a NiteRider headlight, get their Universal taillight. It plugs into the NR battery pack, draws almost no power, and is the brightest taillight I've seen.
The Cateye 1000, the Planet Bike Superflash, and a couple others are much brighter. And they look better from the side too. And they are half the initial purchase price.
Of course then you need to deal with batteries. It does not take too long to catch up to the retail price of the Nightrider if you buy alkaline batteries. If you buy a charger and some rechargeables, then you are up to the price of the Nightrider anyway.