Elastic and bouncing transitions in scriptaculous
Scriptaculous has a lot of transitions, but in some situations, you want to sprinkle up a dull animation, applying a different, custom transition type.
Back in 2003, Robert Penner wrote the easing equations, a set of math formulas in Flash Actionscript released under the BSD license, that simulate various types of physical effects, the most notable are the overshooting elastic and bouncing ones. For an example, look at the demo here.
Three years later, Ken Snyder adapted the equations for scriptaculous, enabling builtin and custom animations to use these new nice effects as transitions. However the Penner easing equations were highly configurable, where instead in the Snyder ones you can only set the duration, because the other parameters are fixed in the source code. Also, not all (indeed, only a few) of the transitions have been ported, and their names have been changed too.