Well, no more: Industrial designer Adrian Van Anz has created a stylish, retro moto-bike that looks like a cross between a Ducati and a Schwinn. Behold, the Derringer Cycles:
Derringers can be pedaled as a traditional bicycle, propelled via engine power, or pedaled with the assistance of engine power. While under power, the pedals can also remain stationary, allowing you to operate in the style of a traditional motorcycle. Capable of fuel economy ratings that can exceed 150 mpg, Derringers are the first product to take the compromise out of environmentalism ...
http://www.derringercycles.com/bikes.htm - via diskursdisko
From the Upcoming ueue, submitted by diskursdisko.
Check them out at:
http://www.imperialcycles.blogspot.com
I found spookytooth a while back when looking into adding an electric motor to my bike for summer commuting. The electric is a nice option, but limits your range a bit.