We can't possibly have a list of fast things and not include Usain Bolt, the world's record holder for human speed. And how fast is the world's fastest person? His record is a 9.58 second 100-meter dash attained at the 2009 track world championships. That's a max speed of 27.4 mph (44 kph) and an average speed of 23.4 mph (37.7 kph). In other words, if Bolt and I were in a race, then by the time you read this entire sentence you'd find that Bolt was starting a victory lap before I even had time to finish the candy bar I was probably eating.
Interestingly, scientists have discovered that Bolt isn't simply the peak of aerodynamic perfection. They found that less than 8 percent of the energy produced by his muscles are used for motion, and that the rest is absorbed by drag. Factoring in the weather conditions and altitude at the time, they figured out that Bolt was actually less aerodynamic than the average person [source: Sandle].
Which, as the researchers point out, make his feats that much more insane. His body is powerful enough to overcome worse-than-average drag to be the fastest person on the planet.