Julie's suggestions are right-on and I'd add Dr. Sears's Discipline Book or Elizabeth Pantley's No-Cry Discipline Solution (she consults heavily with Dr. Sears).
My 3-year-old was recently displaying strong-willed-child tendencies (read: extreme brattiness LOL) because, we suspect, of the new babies (twins!) so I went to Amazon.com, typed in "strong willed child" and got a few hits. We started with Parenting the Strong-Willed Child by Rex Forehand and Nicholas Long. It's a 5-week program, but we stopped with week two as that solved our problem. It's a fairly gentle program with plenty of room for parent improv, plus they don't advocate spanking.
For activities, we like John Lithgow's Lithgow Palooza - fun stuff with the bonus that most of the activities use stuff you'd have lying around the house.
(Julie, I'm looking forward to your Bringing Up Boys suggestion!)