Sure, there are plenty of consumer-focused gadgets in our Insert Coin competition. But at least one group has a much more altruistic vision. Public Lab wants everyone to have a spectrometer in their home that allows people to detect pollutants in their environment. The heart of the Homebrew Oil Testing kit is simple enough: a refractor that attaches to the camera on your phone. The cheapo version can be made from a DVD and a folded-up piece of cardboard, but there's also a heavier duty plastic model in the works. The other hardware component is a simple light source. In this case: a Blu-ray laser. If you want to know what sort of foreign substances are floating around in your water, you shine the light through a sample of it and into the spectrometer strapped to your phone.