All over town in any garden shop they sell all kinds of self watering planters. They are also at a great price.
Now you can purchase pretty glass self watering balls at about a dollar a piece. I have found that they clog up with soil and your plant dies.
While waiting in a doctors office I picked up a magazine that had a piece on making your own self watering planters out of water and soda pop bottles. These work great at a fraction of the price and keeping plastic out of the land fills is a green added bonus. They are very simple to make.