This article on Treehugger.com caught my eye. Designers Lai You Cheng, Liu Kai Ping & Liu Chen Guang have come up with a power saving device, which uses power. Sounds wrong, but let me explain. Suppose you are using a shaver with a plug. When the device is turned on, it's business as usual. When the device is turned off but plugged in it emits an irritating noise.
This is a cool idea, but maybe there is a better way of doing it. I really like how simple and obvious the idea is. Why hasn't someone done it before? Then I begin to think just how much would I hate using this device? Could I come up with a better design?
From a does it work perspective, it certainly would. Although, suppose you ignored the noise, or were not present for it, then it would draw additional power and waste more power than just leaving the device plugged in would.
The Treehugger article brings up the point that the design lacks universality; ie, what about a deaf person? And in terms of simple design, why not just cut off power entirely? Food for thought.