When two different people sent me this link, I realized that it had to be shared.
The Eye of Science gallery has all kinds of pictures taken by microscopists.
I am a great fan of microscopic crystals. Here are crystals of every shape and kind - with some lovely views of snowflakes. Plus, there are wonderful pictures of bacteria (E. coli, Leptospira, Streptococcus pneumoniae) the SARS virus, diatoms, pollen, fungi, parasites, cat embryos, hornets, bone tissue, nylon, and more.