Gadget store Think Geek has the USB Microscope back in stock.

The USB microscope can display things 10X, 60X or 200X enlarged and the image can be viewed on the computer monitor. Snapshots, video, and time-lapse movies are possible with this accessory.
The resolution of the images is 640x480 pixels. This is definitely a great gadget gift for young scientists.
The QX5 is available at Think Geek for $79.99.
The USB Microscope QX5 comes with a USB cable, Stand, Specimen Jars, Sample Slide, Tweezers, Eye Dropper, Slide Clip, and Software CD-ROM

We reported about tons of not so useful USB Gadgets in the past.