Andrew Lathrop developed a way to make a cheap digital camera's CCD sensor detect radiation.
There are plenty of DIY camera mods out there, but this is the first time we have ever seen anyone create their own radiation detector. Lathrop's technique involves covering a couple of layers of scintillator in a reflective material, placing them in front of the camera's lens, and then light sealing it to the best of your ability. Scintillators are materials that when hit by radiation, they luminesce. In other words, when hit by invisible radioactive particles they emit visible light.