Runnersworld.com published a simple method to discover if you have a foot with a flat or high arches, useful to choose the right pair of running shoes.
The beautiful illustrations are realized by Dan Fuehrer:
Pour a thin layer of water into a shallow pan.
Wet the sole of your foot.
Step onto a shopping bag or a blank piece of heavy paper and stand on that leg.
Step off, look at the shape of your footprint and compare it with this images:
NORMAL (MEDIUM) ARCH — Most runners with this pattern can wear just about any shoe.
FLAT (LOW) ARCH — Usually, we would recommend shoes with more stability
HIGH ARCH — We would usually recommend you use a well-cushioned shoe with little or no arch support or stability features.