One that I found effective is for me to just take the child for a car ride and talk.
Some say it's the vibration from the car, others say it's the time away from any distractions such as TV, Video Games, Computer, IPod, etc.
Either way, my kids usually calm down and stop misbehaving after our car ride together.
Eye to eye contact helps a lot too.
I've included a photo below of one of my sessions with my son, in case you would like to use the technique.
People, this is just funny....I don't practice this and this is not my child. I got this email from my friend Emily today and really needed a good laugh.
Warning: Please don't try this at home. Much of the action depicted and/or described on this post is potentially dangerous. Virtually all of the riders seen in this photo are experienced professionals. Do not attempt to duplicate any stunts that are beyond your own capabilities. Always wear the appropriate safety gear.