For the kids at the restaurant while you're waiting for your food: DIY busy wallet! pick up a cheap wallet. fill it with pictures, scrap scrapbook papers, stickers, a pen, etc. ***CJ loves taking apart our wallets.
Peter Walsh holds up a Snapfish bound book of kids' art projects. "Take digital shots of your child's art work, then upload them to 'Snapfish' to make a picture book. You COULD then toss the piles of artwork, but save the book.
Laminate a set of flash cards, put a binder ring around them, and toss them in your purse with a dry erase marker to entertain little ones. I don't know about the dry erase part but LOVE the binder ring!