So, I’m behind the times by a few weeks on this one, but I just have to tell you all about the winning photographs in the 2011 Nikon Small World Photomigrography Competition that I read about in this article and photo gallery in Popular Science. They’re amazing! For example, sand:
Yanpin Wang's photo of sand at 4x magnification.
I’ve had a particularly fun time browsing the Nikon Small World website, which features a gallery of incredible images, a photo-of-the-day and a daily 5-photo Identify the Image quiz. You can even get your very own calendar of Small World images.
Dr. Donna Stolz's collage image of stained animal cells assembled into a wreath.
The next competition deadline is April 30, 2012 and features both still image category and a Small World in Motion (movie) category. Click here to enter your work!
biocreativity 
These are amazing! I never knew sand was composed of a bunch of different sea animal parts, etc.