I am currently doing a literature research on Wireless Sensor Networks. Basically, those sensors can be very small and cheap and measure everything from your heart rate to wildfire occurences or enemy combatant movements.
This is an exciting research area which is based on how the communication between those little guys should be done. I like it because they provide simple models whith which decentral communication can be simulated, but these models are also meaningful, because there are applications around the corner (and you might even get to try them out in reality if someone gives you a bunch of those sensors).
Well, the assumption is that Wireless Sensor Networks will be abundant in 10 years. Put them in cloths and you have smart underwear. Throw a million of them off a plane and you can have a lot of cheap and error-resilient knowledge of the environment.
Well, at least until all their little batteries are down.
My point today is: What if we throw a lot of them off planes and use them until they are out of power? What if we do this a lot? Seems likely. It's so damn useful, in every branch of life, from military to environmental observation.
Maybe Wireless sensors will be the junk of the next decades. They might be everywhere, lying around, polluting, rotting. We are going to tell our kids not to pick up old wireless sensors and the vets will get them out of our dogs intestines.