The hamstrings may be the forgotten muscle in the body, but not only do they help you run faster and jump higher, popping hamstrings leading up to a good bum simply look pretty good. So whatever your motive, you should be working them out, and the stiff leg deadliest is a great exercise for it.
Here you can see a video showing correct technique.
The deadlift is a great exercise that hammers the hamstrings, and why it works so well is fact that it challenges the hamstrings eccentrically as well as concentrically. Eccentrically which is essentially lengthening the muscle under load, is the opposite to concentric, and we are stronger eccentrically. During the lengthening phase of a lift, less fibres are recruited, which means there is more strain on each individual fibre. Damage occurs, repair occurs, adaptation occurs and you get more muscle. Voila.
This is a variation, the single leg stiff leg deadliest. Add some weight to it and you will have a very sore hamstring the next day.