A friend got a USB "microscope" camera for Christmas, but couldn't use it because it's not compatible with Macs (contrary to the specifications listed on Amazon.) So he "returned" it to Amazon, who refunded his money and told him to keep it rather than ship it back. So he gave it to me.
It's kind of neat. It a lot like those Magic Eye cameras that you could connect to the tv. It has a macro lens and a ring of LED lights to illuminate the subject. It's not really a microscope but does take impressive macro shots.
Here's a detail of the border of a five dollar bill. I never knew those little lines were actually printing.