I have been looking for a way to light up the flagpole on my recumbent trike, and found a product that looked like it would work, the Arizona Whip. Jerry at arizonzawhips.com was very nice to work with, and I got it hooked up this past weekend. The whip is 5" tall, and is of clear lexan. Inside the clear tube are 24 LED lights, 12 facing forward and 12 facing backward. Each side has a red group, and a yellow group, and on one side the red and yellow groups of LEDs flash on alternately. Jerry has other color configurations, including a red, white and blue one. The whip screws into a clamp that grips the 1.25 inch tube of the rear wheel fork. The clamp is for 1.5 in. tubes, but with some rubber and duct tape shimming, it grips the 1.25 inch tubing nicely with one Allen bolt for tightening. It extends up through the frame and clears the panniers, rack, seat, and headrest nicely. These pictures show the whip in daylight, and the clamp attached to the frame.
I ran a switch forward to the left hand grip, so I can turn it on and off from the seat. It runs off a 9 v battery. I have not ridden it to work yet, so I don't know how long the 9 v battery will last.
The picture below is how it looks at night, from the rear. The bike is facing not quite straight, and the bag on the rack is blocking one of the LED lights. The headlight is shining across the street at an angle, and provides lots of illumination.
This sucker is not cheap at $150, but if I can get noticed by a car either ahead of or behind me, it will be worth it.