Here's an invention nobody was asking for: the solar toothbrush. Yeah, I know, most toothbrushes don't require any power at all, let alone power from the sun, but this one does. Apparently, it uses the sun's rays to clean your teeth without any toothpaste necessary. Awesome.
Call me crazy, but I don't think I've ever been standing in the sun while brushing my teeth. I'm usually, you know, in the bathroom standing at the sink. I might be really weird and this might not be the norm, but I kind of doubt it. Using power to ditch toothpaste? OK, I'm listening. Requiring that said power be solar? Get out of town.