Exactly what it says, a barcode reader. This one will cost you nothing.
Try it out :-) Please feel free to make changes.
zxing.MonoTouch - https://github.com/martinbowling/zxing.MonoTouch MonoTouch.Dialog - https://github.com/migueldeicaza/MonoTouch.Dialog