Knitting and crochet supplies...you can often get these as a kit so they get instruction and enough material to make one cool thing.
Books on CD.
A photo album with little journal entries from you about their years so far.
Art supplies-- you can often find *awesome* art kits for very little money at Sam's during the holiday season. Make sure to include watercolor paper and a sketchbook with charcoal pencils.
Origami paper and a book on paper folding.The Daring Book for Girls. The Dangerous Book for Boys.Watercolor for the Artisically Undiscovered
(by Klutz). My two older girls and I each have our own copy of this. It's so much fun, and everything you do in it looks great!Drawing for the Artistically Undiscovered
(also by Klutz). My girls also have a copy of this, and so do I. I love these books.
Fun tights (you can often find them on super-sale at Lands End). A book on ropes and knots, some carabiners and ropes.
A fishing pole and book about local fishing.
Handmade paper kit.