I've always been put off 'digital' sudoku gadgets as I prefer working with good old pen and paper, but I bought one of these the other day and found it really good - loads of hand-made puzzles, and dry-wipe board for filling out answers.
My 10 year old has really got into sudoku with this thing too, starting out on the gadget's 'junior' squares.
Anyway, thought I'd share it with you:
http://tinyurl.com/9m896