Watch this video:
http://users.verdeonline.com/ace/jeep/rolling.wmv "Jeep wranglers come with a cheesy half-cage that includes a crossbar behind the front seats and two bars that extend rearward over the rear seats. The stock cage is completely inadequate for anything more serious that the most simple, beginner trails. Basically, if there's any chance of rolling the vehicle or flopping it on the side, the cage should be upgraded.
This guy's problem though, is that he bought a "bolt-in" roll cage upgrade from ORF, which basically adds the front support bars you see in the video, where the windshield frame would normally be, with some tubes extending back to the stock rollcage. Of course, this cage is sold by the company as a safety upgrade. This guy thought he was well-protected, but look at how the cage just folds up in what would be considered to be a medium-impact roll. Scary as hell."
Not to mention the fact that he stuck his leg out... jeeze.
Fortunately, he came out alive and unhurt (he pulled his leg in at the last time).
A roll cage is moving up on my list of things to do on my Jeep. It's approaching the point where I could get into situations like the above, especially with lower gears and a little bit of axle-wrap. The roof would probably end up caved in, and windshield would be broken, but all occupants of the vehicle would be alive and unharmed and able to laugh about the whole thing after removing the seat cover from their backside.