Waste of money. The Jeep is already tuned as lean as it can be without burning up, so the chip isn't going to cut down on fuel consumption. And absent an engine swap or substantial internal engine modifications, more horsepower = more fuel consumed, period.
As for fuel economy, there is only so much you can do to help a brick on wheels be more efficient. I've found the best course of action to be keeping up on preventative maintenance, driving gently and slowly, making sure the tire/gearing combination you have makes sense, running synthetic oil in everything, leaving the Jeep un-lifted, and staying off the loud pedal as much as possible.