Spider Animation

Here's a cool tutorial that I came across that shows how to use set driven keys to build a spider rig. I like it because it's a very simple setup that produces a complex looking result:

Jan Sandström: Spider Animation

As with any automated animation, if you were to incorporate this setup into a production rig, you would want to include switches to turn it on and off or blend it with hand animation. Automation is great, but the animator should always be in control. You could use these same principles to automate secondary animation on a robot or all kinds of different rigs. (Picture gears and pistons that automatically turn and pump when the animator raises the character's arm). I'd probably use expressions instead of set driven keys personally, but the basic principle is there.