The Robot Builder's Bonanza by Gordon McComb

This is the grand-daddy of all modern hobby robotics books.  Long before LEGO Mindstorms was big, the first edition of this book was guiding users on how to adapt and program their Apple II computers to run household robots.   This second edition has been extensively updated and covers both the physical hardware you need to create your own robots (wheels, servo motors, drives, etc.) and the programming to make it all happen.  Including a new section on LEGO Mindstorms and stamp-sized microcontrollers, this is the single best book for any amateur robotics hobbyist.  This would make an excellent weekend project for parents and kids.  Highly recommended.