We've showed you how to build your own camera crane, but if you're looking for an easier way to get steady video, this monopod mod should do the trick for less than $US30.
This hack is based off the $US400 Steddiepod, which, while incredibly smooth, is a bit on the expensive side. If you don't need to be too serious about how steady your shots are (i.e. if you're just doing it for fun and not professionally) you can sacrifice a small amount of steadiness for a much cheaper DIY solution.
The GlidePod (as its creator Eric over at Tech Tilt calls it) is basically a monopod with some PVC pipe connected at the end to act as ballasts that keep the shot steady. It also sports a ball head setting that, while not as good as the SteddiePod's head, will also help keep everything fluid. You should be able to get all the pieces for just about $US30, with just a trip or two to your local discount shop. Check out the video below for some sample footage — it's not as steady as using a crane or a track, but compared to walking camera-in-hand, it's definitely a step up. Hit the link for the full instructions.