Intel’s discontinued QX3 Computer Microscope has been licensed by Prime Entertainment, and is back on the market. It’s aimed at kids, but it’s pretty powerful for a toy: it has up to 200x magnification, connects to a PC through a PC for real-time specimen viewing, and you capture video and still images of whatever it is you’re looking at. Amazon still has a few of the old Intel ones for cheap.
UPDATE: A reader writes in with the URL for a site that has OS X drivers for the QX3: http://homepage.mac.com/aireck/. Thanks Rob!