Open Source Intelligence
Technocrat pointed me to this story on Village Voice, a title I used to read assiduously in my younger days. It's about how a network of planespotters have put together many of the pieces that go to make up the shameful jigsaw puzzle of the CIA's "torture taxi" operation, used for moving people around the world to be held and tortured without judicial oversight.
What's fascinating is the way that tiny, apparently meaningless contributions - a photo here, a Yahoo search of a plane number there - when put together, can help create something really big and important, just as open source projects pool the work of hundreds or thousands to create vast and astonishing achievements like GNU/Linux or Wikipedia.