Kingston 4GB Data Traveler USB 2.0 Flash Drive - £17.99 delivered @ DVD.co.uk
Good price for 4GB drive but may be dwarfed by the recent 2GB deal from Amazon (lol). Go via Quidco for further cashback.
Description : It works with virtually any device with a USB port - even cross-platform from Macintosh to PC and vice versa. Backed by a five-year warranty and Kingston's legendary service and support, the DataTraveler is a reliable, inexpensive solution for carrying files or your next promotion.