A wicking bed is a kind of self-watering planter built so a water reservoir in the bottom provides a constant source of moisture which is wicked up into the soil. This is supposed to reduce the amount of water needed for irrigation. I made the bed pictured above from an old plastic storage tub and some extra plumbing bits. I partially buried it in an existing raised bed and covered it with rocks to improve the appearance and help with moderating the soil temperature. Currently growing in the bed are Oregano, Basil, Bunching Onions, Longevity Spinach, two varieties of Brazilian Spinach, and a few salad greens. So far it seems to be working well. I will probably make more wicking beds from other old tubs and containers.
More info about wicking beds: Desert to green oasis