EagleTec Nano offers the FD Nano Disk USB to their consumers. The Nano Flash Drive is very small measuring just 9 x 15 x 6mm and weighs just 3g.
The ultra small memory device is available in 4GB and 8GB storage capacity and is going for $22 or $33 respectively. It supports USB 1.0 and 2.0. Check out the product page