http://www.gadgetspy.co.uk/2006/06/29/a-pc-smaller-than-a-credit-card
Compulab, based in Israel, have managed to squeeze a computer on to a device two-thirds the size of a credit card.
The CM-X270L measures just 4.4 x 6.6 cm. In comparison, a MiniPCI wireless card is 6.0 x 4.4 cm - just half a centimetre thinner.