Coil and Recoil
The trick is the dedicated contacts in the hot shoe - 3 for Nikon and 4 for Canon. They pass the coded signals back and forth at the speed of light. It is perfectly feasible to take flash pictures all day and not touch any of the controls. Yay.
But when you need the direction of the flash to be different than stuck on the top of the camera you need to get that same control at a distance. Here is where Promaster comes in. They make double-ended TTL cords for both the Canon and Nikon systems - you can get them as short as 150 cm and as long as 10 metres in either coiled or straight form. Attach one end to the hot shoe, put the flash in the other end and shoot macros, street shots, product shots, and Hollywood portraits.
In-store right now.