Do you have $10 and a few minutes and a burning need for a microscope? You do.
But why would I need a microscope? you say.
You do! Examine plant cells, check out the sharpness of your knives, or just take some awesome photos. It's easy to make and looks rad and even if you never use it you can put it on a bookshelf as a conversation piece.
You can check out Instructables for the full list of instructions, but basically the whole process involves building a stand with plexiglass slides, then backlighting those slides with an LED. A lens from a laser pointer does the magnifying. The magnification on the DIY 'scope goes up to 175x, which isn't half bad--enough for some simple DIY experiments, at least. Judging from the video, it works better than you'd think. Wonder if you can diagnose malaria with it.