According to Wikipedia: The one-inch punch is a punching exercise from Chinese martial arts (kung fu) performed at a range of 0–15 cm (0–6 in). The one-inch punch was popularised by actor and martial artist Bruce Lee. It is designed to improve punching power and technique.
The one-inch punch was also featured in the film Kill Bill Vol. 2.
Man-oh-man, if I can master this... I think I might quit my job and take my dog and pony show on the road.