My friend Richard Kadrey introduced me to infra-red photography. Sensors on digital cameras can detect infra-red, but normally are shielded from it by a protective filter that resides as a thin layer over the chip.
You can hack a camera by removing the layer, but it is easier to buy a Fuji IS-1, which is infra-red-ready. If you use a lens filter that blocks the visible frequencies, the camera displays an image that consists of infra-red transposed into the visible spectrum.
Vegetation reflects almost all light below red, and thus appears “white.” Conversely, the upper atmosphere does not refract infra-red, and thus a blue sky appears “black.” An unexpected effect is that most fabric dyes reflect infra-red, so that a crowded sidewalk appears to be populated entirely by angelic people dressed in white.
During 2007 I drove across the country and took a bunch of infra-red photographs. The Southern states looked especially good, because they contain so much vegetation.