Here's a DIY way to make your tail and brake lighting stand out much better without spending a lot of $$$. (Due to the limitations of YouTube the strobing is a little choppy in this video but you get the idea.)
BMW K75 K100 K1100 Enhanced Tail & Brake Lighting (http://www.youtube.com/watch?v=YDeEPTyOBfo#)
Step 1) Do the Easy, Inexpensive Tail Light Upgrade (http://www.motobrick.com/index.php/topic,3314.0.html)
Step 2) Obtain a brake light strobe. (a.k.a. flasher) There's a few varieties out there which can be had on Fleabay for <$20 shipped. The one I used for this bike is one that strobes eight times and then goes solid. I'd recommend getting the smallest one you can find so it fits inside of the area behind the tail light lens. If its too big for that then you'll need to drill some holes for the wiring in the tail cowl "wedge" and install it in the tail cowl storage compartment.
Step 3) Buy or make a normally closed relay. Here are your options:
Buy: Buy a standard Bosch type relay with five terminals. Make sure it has an "87a" terminal as some five pin relays have two 87s instead of an 87 and an 87a. (The 87a is the normally closed terminal.) These are kind of bulky so it probably won't fit behind the tail light lens so you'll probably need to drill some holes in the tail cowl "wedge" and install it in the tail cowl storage compartment.
Make: How To Make Waterproof Mini Relays (http://www.motobrick.com/index.php/topic,1146.0.html) In general there are two types of those PCB relays available, a 2 amp version and an 8 amp version. I'd recommend getting the 8 amp version if you're running an incandescent brake light bulb. (If you live in the US and don't want to do this then I will sell you one pre-made for $15 shipped.)
Step 4) Wire it all up. Since brake light strobe wiring varies from model to model, the wiring in the diagram below is simplified but all brake light strobes have two things in common: a 12V+ input for the brake light and a strobing 12V+ output. The numbers on the diagram below correspond to the standard Bosch relay terminal designations if you decide to use one of those.
(http://i1221.photobucket.com/albums/dd470/Motobrick/lighting/tailbrake/braketailstrobe.jpg)