Did you know there’s an entire site dedicated to tablets with full-size USB slots? True story: http://www.tabletswithusbports.net.
Slightly tenuous link out of the way! You might fancy this Lexar 8GB USB JumpDrive four pack for £10.71 from Amazon. They come with a pen and write-on labels, but you can easily identify what’s on what – in theory – by the different colours: blue, orange, purple and green.
(Thanks to oscarcat at HUKD)