I first saw this book on someone else's bookshelf, and just had to track down my own copy. Since then I've bought several more, because the children love them! So much better than the colour-the-spaces-and-don't-go-over-the-lines books, these books encourage children to use their imagination. I tried to get one for myself, but the children saw it and I lost it again!
Draw the new fish that's been discovered, draw the picture that goes with the report of the first alien to land on earth, draw your nightmare, draw your daydream. Simple enough for a young child to use (it helps if they can read the few words of instruction) and inspiring enough for older children, up to teenagers (older than that will probably think it's not "cool" until they reach adulthood!). Because you're drawing your own designs all the time, the children are even asking for second and third copies of the book.