I always wondered why my computer’s power light decided to annoyingly flash at me whenever I put it into standby mode. Turns out, it might have been an effort to get me to turn it off properly:
Our DVD player has (to me) the most irritating standby light that I have ever seen on any device. When on, the light is constantly illuminated, but when in standby the light flashes continuously (at a slow rate). This drives me mad, but results in an interesting action it causes me to turn it off at the plug when I am not using it (which is most of the time). Suddenly one little flashing light has resulted in more energy saving than having no light.
It’s a great example of what is called design with intent.