Asking your sister to come by your house and water the plants while you spend the next three days at an out-of-town conference is like squeezing blood from a stone. Never gonna happen. Well, stop asking and just pick up a couple pieces of Water from a Stone.
Designed by Casey Schneider, it's a stone-shaped glass container that will water plants on its own over the course of the next four days. Unlike autonomous "waterers" we've seen, there's nothing hi-tech about this -- it just slowly rations the water inside the container so you only have to fill it once to keep your plants nourished while you're away.
To use Water from a Stone, simply fill it up with water and set it down on your planter, making sure it's positioned so the release hole isn't obstructed. You may want to test it out a few times to get the correct angle (bubbles will rise from the release area when it flows out) -- incorrect setup can lead to water either not dripping (your plants die of thirst) or flowing out too fast (they drown or something). Each one can only water the area where it sits, of course, so you'll probably need a few if you have large planting boxes or multiple planters in your digs.
Construction is hand-blown glass, with container space for up to 7oz of water. It's a whole load of good-looking, too, so it can make for a great shelf decoration when not in use.
Water from a Stone is available from Kikkerland, priced at $13.