I love the sticker idea.
And Jaronimo, I just use a sharpie to make little hash marks with three circles-- a full circle for 'closed', a half-black circle for 'half', and an open circle for 'open'. But like Troy, I don't actually use them that frequently, as most of my cooking is cone wide open. But when I'm smoking something or trying to reduce the heat, it's pretty nice to be able to know where the vents are (If I'm maintaining temperature at, say 3/8ths and I need to turn the food or add coals or something, I'll choke the grill down completely for a few minutes before opening back up to 3/8).