How to Make a Rubber Band Racer, available online at http://webpages.marshall.edu/~bady/rick/elastic2.htm

Let ‘em Roll, Newton’s Apple Activity Page, available online at http://www.ktca.org/newtons/9/slink.html

The Motorized Spool, available online at http://www.iit.edu/~smile/ph9601.html

Come-Back Can, available online at http://sprott.physics.wisc.edu/demobook/chapter1.htm