Anyone with a green thumb will tell you that plants need both water and light to grow, but finding a nice sunny spot in most homes can be tricky. Belgian sculptor Stephen Verstraete has come up with the perfect solution, by putting his houseplants on robotic carts that automatically seek out the sun as it moves around the house.
Verstraete says that he built each of his robot plant movers using a recycled toy electric car, a light sensitive photo transistor, a couple of ICs and a few extra parts for the grand sum of about $10 each. That's pretty cheap even if you have to go out and buy a new toy car to use as the foundation.
Over on his Instructables site, Verstraete includes the full parts list and circuit layout, just in case you're inspired to try and make one for yourself. Better still, perhaps his idea will convince a commercial manufacturer to make something like this you can buy.
Just don't let your cat know, he still hasn't forgiven you for that time you came home with a Roomba.