This year I would like to purchase a few ollas for the garden. Ollas are unglazed clay pots that you bury in the ground (leave the neck above the soil), fill with water, and the water seeps out of the pot slowly to keep your plants continuously watered. This article has a great description and pictures of how they work. It looks like you have to re-fill them every day, though. I don't water that often, but maybe I should be?