A few months ago I had a building need for a fixed gear bike. It progressed when the movie Premium Rush came out, by then I was dreaming about them, and it was driving me mad! I already had a bike that I had planned to turn into a fixie, which I dismantled. I also custom built a 27 inch fixed wheel, because I knew 27 inch tires are super cheap (and when I learned how to skid brake, I took advantage of the cheapness).
Fixed gear bikes are the purest of all bicycles out on the market today. Fixies were the first bikes to be built, and were used by everyone, that is until the automobile came around. Most bicycles today use a freewheel which allows you to coast or cease leg movement without a wreck. Fix gears on the other hand, do not have a freewheel, if you were to stop your legs, the bike would stop. But for a fixed gear it takes a little more effort stopping your legs.
Here is a bit of food for your thinker: when running, do you ever cease leg movement to relax your legs? If you were running at a high speed and just stopped, you'd trip and fall. Now explain to me why you would ride a bike any differently. Therefore a fixed gear bike is the bike to have!