Not exactly a pen drive, but USB Ext SD card reader
http://www.ebuyer.com/customer/prod...WN0X3Byb2R1Y3Rfb3ZlcnZpZXc=&product_uid=75233
and then a 16mb SD card
http://www.ebuyer.com/customer/prod...2hvd19wcm9kdWN0X292ZXJ2aWV3&product_uid=49349
total cost, inc shipping: £3
Not bad if you don't need to carry much data
http://www.ebuyer.com/customer/prod...WN0X3Byb2R1Y3Rfb3ZlcnZpZXc=&product_uid=75233
and then a 16mb SD card
http://www.ebuyer.com/customer/prod...2hvd19wcm9kdWN0X292ZXJ2aWV3&product_uid=49349
total cost, inc shipping: £3
Not bad if you don't need to carry much data