I listened to this podcast on IPv6 a while ago. It talks about a lot of things, but in particular talks about an interesting experiment to generate a micro weather map by assigning IPv6 addresses to the wipers of taxi cabs. The idea is to correlate the location of each cab with the movement of the wipers to figure out the areas that are raining. I think that's a pretty interesting experiment.

My coworker told me a somewhat related story. Apparently one can buy a device that can measure certain weather conditions (temperature, etc), install it at home, and broadcast the result over the Internet. This becomes very interesting if enough houses install the device, since we'll then be able to generate a real-time weather map that are more accurate and more micro in scope than the traditional weather map we get today.

It's interesting to think of these examples as Web 2.0 style experiments, because they take advantage of "collective intelligence" in a fundamental way. This allows them to provide better services than a single provider can provide.