Here is a link to what is essentially an air bladder that can be used as a jack. Would seem at first impression to have some usefulness, provided you have an air pump.

http://toolmonger.com/2008/01/28/lift-a-ton-and-a-half-with-a-bicycle-pump/

Edit for link to the manufacturer: http://www.matjack.com/quick.htm

Both high and low pressure air bags are used in rescue, but it is important to crib with size appropriate cribbing in case the air bag fails.

Pete

Pete,

That is a good reminder for working under any lifted object. If you jack a car up on a hand hydraulic jack, using a shop lift, or an air bag like one of these, make sure you are not relying on only that tool when you get under that heavy object. Get some jackstands, cribbing, blocks or something strong enough to keep that object in the air.

I use a jack so infrequently, I do not know that I would've remembered to do that if I had to use one today.