Measuring speed in the digital age
In the digital age, accuracy and speedy calculations come from using powers of two. You also want to stick with integers to avoid rounding error. Therefore I propose that we measure speed in nano-furlongs per mega-fortnight. The conversion from metres per second is fairly simple - 1 m/s is approximately 264 nFurlong/Mfortnight.
This means that we can measure incredibly slow speeds with great precision - down to of the order of 10-19 m/s without having to enter the dangerous world of floating point. And of course we can easily measure all the way up to the fastest possible speed, that of light, which is only about 292 nF/MF. This provides ample room for further expansion of the measuring stick if Mr. Einstein turns out to have been wrong. A 128-bit value would let us measure speeds up to 1010 times that of light, in extremely small increments.