An anonymous reader writes "I've always wanted a geiger counter to play around with but thought they would be too expensive for mere mortals. But after a quick Google search, it looks like I was wrong and some ex-Russian models are available for pennies. I even found instructions on how to make my own doseometer. So I thought I'd ask Slashdot: What makes a good geiger counter? What features are most useful? Let's put together a geiger counter buying guide!"