The Characters Weren’t Created Yellow By Accident
Creator Matt Groening told the BBC, “An animator came up with the Simpsons' yellow and as soon as she showed it to me I said: 'This is the answer!' because when you're flicking through channels with your remote control, and a flash of yellow goes by, you'll know you're watching The Simpsons.”
(i think that was from producers' commentary on one of the episode DVDs)