I have looked at outdoor fire pits before and there are many great pictures of some inspiring examples. You can either buy something from your local DIY store or make one yourself as a few people have done below.
A fire pit is not always about the heat it generates, this after all goes straight up! But there is something enchanting about the movement of fire that makes us fascinated by it and the David Harber bowl at the bottom is a good example of this. It has a pretty pathetic flame and would barely heat a marshmallow but is by far and away the most expense one there.