The Groasis Waterboxx was the grand award winner in Popular Science’s 2010 top 100 innovations list. The base has a water reservoir which you fill once or very rarely. Any rainfall or morning dew runs down the top of the lid to water the plant, and the condensation from the reservoir collects on the underside of the lid and serves to water the plant in dry times.
At $275 for 10, it seems a bit pricey for it’s intended use in poor, arid nations, especially considering you could likely make a passable version of these out of old tires and trash can lids, but I see no reason it has to be an eyesore. I can see a nicer version of this having use in parking lot plantings in semi-arid cities like Los Angeles, or for newly planted trees along highways.