Ductigami: The Art of Duct Tape by Joe Wilson If you can get it, buy the first edition--it has instructions for making unusual things you may not have thought of before, like an apron and a pencil belt. The second edition has the same projects, but it has adult humor in it too (so if your dad makes you yawn, don't buy this one).
Got Tape?: Roll Out the Fun With Duct Tape by Ellie Schiedermayer. This has a number of basic projects with a clear layout and good directions. We'd recommend it for the beginner and for those under 13.