The recent book "Buy, Buy Baby," by journalist Susan Gregory Thomas, points out that kids don't need expensive playthings to get smart and have fun. But what parent—or grandparent—can resist a spending spree or two? "The key is to choose toys that encourage movement of some sort," says New York City-based physical therapist Deanie Barth, who works with infants and toddlers. It can be something simple like a crayon, which encourages dexterity, or more complex, like a tricycle that requires kids to balance on one leg as they get on and off. These toys, which Barth helped select for the developmental toy siteebeanstalk.com, will help infants and toddlers crawl, stand, walk, run, jump and hop through their early years. Other good choices include pull toys on a string, which help with balance, and movement games like Hullabaloo. All require close supervision.