Jeffrey Warren at the Massachusetts Institute of Technology has been experimenting with kites, balloons and cameras to learn to take aerial photos without the use of expensive equipment. His Grassroots Mapping project is now studying oil in the Gulf:
The kits used to take the images are extremely simple and incorporate garbage bags, an inexpensive kite and digital camera and a small helium canister. The kites are flown to around 1,500 feet where they snap images of the area below at regular intervals. After the pictures are collected, Mr. Warren works with Stuart Long of the aerial imaging service Gonzo Earth to stitch the images together on a map.
The results are both beautiful and devastating.
Here’s a how-to page on balloon aerial photography.