I first found this image on Chet Ramo's Science Musings blog, and just stopped to look at it for a while. (click on the image to view a high resolution version.)
Check out more details on the equipment here, and the original source of the snowflake crystals images here, and here.
At first glance, it doesn't really look like a snowflake. In actuality, it is an image of several snowflakes of differing conformation (I counted about eight different varieties) that have been sputter coated with platinum at a very low temperature (in order to make them conductive) and then imaged with a Scanning Electron Microscope equipped with a low temperature stage. The resulting gray-scale image formed by the electron beam was then digitally colored just as the old black and white movies have been "colorized" to result in the above "false color" image. Here's a picture of the specific unit that was used to take this image.