I don't know how plausible it is, but it'd be awfully nice if laptops had a way to power USB ports when the machine is off but plugged in. Perhaps this could be controlled by a switch on the side of the case that turns on USB power only.
The use case, of course, is for portable devices that can charge their batteries over a USB connection. Apple has stopped bundling anything except a USB cable with the iPod, and it's pretty easy to find USB power cords for PDA's and cell phones. With this kind of functionality in a laptop, the laptop could become a traveler's one central power adapter, eliminating the need to carry large numbers of dedicated adapters or half-baked partial solutions like the iGo. I can see paying 50-60 dollars extra for a laptop with this feature.
Another way this could be implemented would be to put 3-4 power-only USB ports on the laptop's power brick.