I use a SanDisk 1GB Ultra II SD PLUS Flash memory card as a portable flash drive. The price of the 1GB card has dropped down to only $67 at B&H Photo-Video. A 2GB version will be available soon, see SanDisk Doubles Capacity of Innovative USB-Flash Memory Combo Card. It is an ultra-fast 10MB/second flash memory card that connects directly into a USB port by transforming into a USB adapter eliminating the need for any readers to offload content to a PC.

My Toshiba M200 Table PC notebook has an SD card slot which I can use with this SD card, but I found that using it with the USB 2.0 transfers data about twice as fast. I carry it in my wallet, a much more convenient way of always having a portable flash drive available compared to the bulky key chain or the other more traditional flash drive devices types.