Phantasmechanics has a great reference article on using compressed air to animate props. For any home haunter who is looking to take their attraction to the next level, adding a system capable of moving props quickly and powerfully is a sure way to create some great scares. A basic understanding of pneumatics is necessary, as working with compressed air can be dangerous if precautions aren't taken.
Here is an excerpt:
"Compressed air offers a number of advantages over electrical actuators for haunts, and has accordingly been used for many decades in dark attractions. The hiss of air accompanying a scare was a hallmark of the dark rides I grew up with. Utilizing compressed air is the most efficient method to produce sudden and startling kinetic effects. It is safe to use on damp ground outdoors, allows quick and powerful movements without the risk of blown fuses or overheating, and allows for the relatively simple construction of devices that would be expensive or impossible to duplicate using other methods.
The amount of force generated at the output of an air actuator (usually a piston and rod housed in a cylinder and connected to an object to be moved) by even a modest amount of input pressure can be amazing. If you've never considered an air system because it seemed too daunting, peruse this article and discover the basics. It may be just what you're looking for."
Click here to see the full article.
I admit it. I like to look at props that I'll never (no way in hell) be able to afford (or even store). Some of the props being developed right now are absolutely amazing, but have price tags that make them sooooo hard to justify unless I open my own amusement park (not likely to happen). 
