I had a travel plug adapter (for conversion between US/UK/EU-style) that had a bright blue LED on it to indicate power. I don't know who thought the choice of

I had a travel plug adapter (for conversion between US/UK/EU-style) that had a bright blue LED on it to indicate power. I don't know who thought the choice of blue was a good idea, because as a travel adapter, it would be plugged into the hotel room where the user would be sleeping. /facepalm I ended up taping a piece of paper over the LED.