CONTEST: What well designed common thing goes unnoticed?

With the new book coming out soon, I’m running a little contest on Twitter. Best three answers get a signed copy of How Design Makes The World.

The question: what well designed common object goes unnoticed because it works so well?

Contest closes at 11:30am PST Wed. April 29th. I’ll announce the winners live on Twitter at 12pm.

Leave your entry in the comments or on Twitter. Even if you miss the deadline I’d still love to hear what comes to mind for you.

Here’s the list so far:

The simple toaster oven
Japanese nail clipper
The pencil
The clockface
Yellow dotted line in middle of roads
On road reflectors / Cat’s eye
Bathroom entrances without doors
Mythical bathroom where you don’t touch anything?
Aglets (tips of shoelaces)
Scotch Tape roll holder
Paper Clip
Phillips screw and screwdriver
Cigarette Boxes
Chapstick
Running water
Safety Pin
Hinges
Alphabet
Light switches
Corkscrew
Book
Peeler
Concrete
Toilet Paper
Bidet
Spoon
Stairs
The Metric system
Glass
Handicapped symbols
Chopsticks
Mirrors
Keys / Lock & Key
Hammer
Clothes buttons
Bicycle
Tire pressure valves
Toothpick
Mattress
Glasses
Scarf
Single level mixer (a faucet that controls both temp and water pressure)
Escalator
Waste disposal / recycling
Elevators
Safety Matches
Dog door
Differential gears
Traffic signs
Curb cuts
The dial
The smell added to natural gas
Windshield wippers
Soda can tabs
A mug
Ballpoint pen
Light bulb
Decimal number system
Zipper

Have an interesting one I should consider? Leave a comment.