Everything is always 100% better after a nice little nap, and Wi-Fi is no exception. By allowing smartphones to take sub-second naps while waiting to transfer data, it's possible to double battery life with just a clever piece of software.
You may think that your smartphone is continuously downloading data when you're streaming a YouTube video over Wi-Fi, but that's not exactly how it works, especially if you're connected to a Wi-Fi router that's trying to juggle a bunch of different devices at once. Instead, what happens is that your device gets sent a glop of data, and then waits around while the router serves whatever other devices are connected to it before sending you another glop.
All of this waiting around is just battery life that your smartphone is wasting by being connected to a Wi-Fi access point while not actually doing anything. Justin Manweiler, a computer science graduate student at Duke's Pratt School of Engineering, has figured out that by instructing smartphones to enter a Wi-Fi sleep mode while they're waiting for data, it's possible to cut their power consumption in half.
The system that Justin has developed is called SleepWell, and it's intended to be installed on access points (like routers) meaning that your smartphone can benefit from it without you even having to do anything at all. In fact, you won't even notice that your device is snoozing half the time, you'll just notice that hey, I have a bunch more battery life all of a sudden, awesome!
While SleepWell is designed specifically for Wi-Fi networks, it seems like the same concept could be extended to other types of access points, like cell sites. Basically, any situation where your smartphone has to wait in line to get data could be improved by allowing it to nap, and come to think of it, that's a philosophy that really should be extended to the rest of us as well.