Here is a quick look at Planet Bike's Superflash's 2 different models:
The Turbo Superflash
The Turbo is the top flasher. It has a 1-Watt attention grabbing LED with two, smaller Nichia LEDs for supporting flashes. (In case you are wondering, Nichia is a top-shelf brand of high-quality LEDs. You get what you pay for.)
With 100 hours of battery life and water proof design, you are set for plenty of days of riding.
The Blinky Superflash (2 Designs)
This is the light that I use. I would either clip it to my seatpost with the included mount, or to my messenger bag. Either way, it seemed to work well to attract attention with its .5 watt flash and two supporting Nichia LEDs.
I had been commuting for several months before I got the Superflash, and prior to it, I was wearing 3, cheap, blinking lights. The difference in how cars treated me after dark was immediately noticeable. It was a comforting feeling.
If you think it looks cooler, you can also get the Blinky Superflash in a clear/black casing design. The LEDs are still red, but its a neat design and some people appreciate the variety.