This is one of the most insane natural phenomenon I've ever seen.  If you've never had a chance to see the Purple Martins down in the Shockoe Bottom area in the summer, please do your research and check em out.  They aren't quite as awesome as this video, but they're pretty close.

Powers of Ten takes us on an adventure in magnitudes. Starting at a picnic by the lakeside in Chicago, this famous film transports us to the outer edges of the universe. Every ten seconds we view the starting point from ten times farther out until our own galaxy is visible only a s a speck of light among many others. Returning to Earth with breathtaking speed, we move inward- into the hand of the sleeping picnicker- with ten times more magnification every ten seconds. Our journey ends inside a proton of a carbon atom within a DNA molecule in a white blood cell. POWERS OF TEN © 1977 EAMES OFFICE LLC (Available at www.eamesoffice.com)