A drop of water might look perfectly clean to the naked eye, but get up close and you'll probably find lots of creepy-crawlies. All you need is a laser lit microscope to see it.
Someone going by the name Grenadier over at Terravolt.org decided to create his own, using a green laser pointer, a book, a syringe, and some scummy water out of a handy houseplant.
By shining the laser through the water drop, he was able to see all kinds of stuff swimming around in there. What's not immediately clear is just what the microscope itself looked like, but I suspect is was one of those USB jobs.
I know this was dirty plant water, but I wonder what he would have found in his local municipal tap water?
CORRECTION: An knowledgeable Dvice reader has pointed out that no USB microscope was used. The laser light uses the water droplet as a lens to project the enlarged image. Clever stuff!