Canon Speedlite 580 EX II
This is my flash. It is very powerful, being able to illuminate a subject nearly 200 ft away. I rarely use it at even half that distance, but I do not doubt that I could(As long as I brought a lot of spare batteries!)
This flash is Canon's top of the line flash. It has ultrasonic capacitor charging so there is no high pitched whine after each shot. I like this feature. It also recharges very quickly after each shot.
I use this almost 100% for "people shots" It has a swivel head that can point in about any direction... Bounce time! It has fully auto mode as well as manual from 1/32-1/1. It is weather sealed.
My favorite(but admittedly seldom used) ability is the famous "Stroboscopic" function. This feature emits a burst of multiple flashes very quickly, allowing multiple images of the same subject in one exposure.
There are many things to like about the flash. I have nothing to complain about. That is a high commendation from me!