The number shape system is a method of replacing hard to remember and abstract numbers with an image which is easy to remember. As an example the number one is replaced with an image which is similar in shape to the number '1', such as a pen, pencil or arrow. The other numbers can similarly be replaced and the following sequence is one suggestion for the numbers 0 to 9. Tyre, Candle, Swan, Heart, Yacht, Hook, Elephants trunk, Axe, Hour Glass, Tennis Racket.
As an example, to remember that the number of a house you must visit is number seven, visualise the house door and imagine you are breaking into it with the axe.
The number shape system can also be used as a PegSystem giving you ten pegs on which to hang useful facts. In this case link the ten items to remember with each of the number shape images. You can now recall the items in any order and at random by visualising the number shape for the item you wish to recover and remembering the link.
Wikimedia Commons has a category of shapes for number shape system: http://commons.wikimedia.org/wiki/Category:Number_Shape_System