Spotted on Anthropologie, a clear glass ball to fill with water to keep house plants happy when you go out of town for the weekend:
Above: A mouth-blown glass Garden Water Ball will keep house plants on a drip feed so soil doesn't dry out. It's $10 from Anthropologie.
Above: The Garden Water Ball is 5.5 inches long and 2 inches in diameter. Fill it with water and insert the end of it into soil.
For another ingenious irrigation solution, see Self-Watering Terracotta Planter by Joey Roth.