Inertial Bounce is an expression I use in After Effects all the time that calculates the velocity of an object and uses it to determine the bounce/wiggle of an object as it comes to rest.
Expression found here: http://www.graymachine.com/2010/04/my-top-expressions/
Here is a great XPRESSO set up that mimics the "Inertial Bounce" expression. The "Delay Effector" is great but must be used with other effectors to see it's effects. With this setup you can use the delay effector with any object and just a couple key frames to create inertial bounce.
You all probably know this already but this was a huge breakthrough for me!
Thanks to Tim Clapham for the xpresso: http://www.helloluxx.com/cinema4d-mograph/springy-camera/
Download project file here: http://blog.pluuck.com/2011/06/inertial-bounce/