I'm not much of a "car guy," but this Exhaust Air Jack seems like a pretty brilliant alternative to your normal jacks. Simply plug the hose into your exhaust pipe, stick the balloon under the frame of the car, and let the exhaust lift the car up so you can change the tire. Apparently, it's strong enough to lift a three-ton vehicle 18 inches for up to 45 minutes, which should be enough time for even the most inept of us to change a tire. Hit the jump for a video of it in action.
Actually, these work quite well. A couple of the guys in my 4x4 club have them, and we put them to good use on nearly every outing.
Where we go, a standard bottle jack is useless (not to mention our rigs are far too tall for the stock jack), and often times the terrain is too loose, soft, etc. for the standard farm-lift type jack we generally use.
These bags are made of a really durable material (haven't seen one pop yet, even when used in a boulder garden of fairly sharp rocks), and have a check valve to prevent sudden deflation were the engine to stop or the hose fall off. That same clever valving allows the bag to inflate without supplying too much back pressure, so the engine keeps running fine.
So far, I've been really impressed with their uses in off-road situations. However, having said that, I also agree that on pavement the standard bottle or scissor jack is faster and less hassle (unless, like I said, your truck is too tall for the stock jack).