This is an interesting thread, at least it is for me b/c I got my XJ broken into in my driveway and they tried (unsuccessfully) to steal my CD receiver. They broke my driver's door window to get in, but my dad's ZJ was unlocked and they took the faceplate off his CD receiver and some cash from the glove box...go figure. Morons. But ever since then, I've wanted to rig up a really good security system for my XJ so whoever tries to steal anything from it again will regret it! My guitar amp tech told me he could rig up an alarm that would shock someone if they tried to break in...
Of course, this happened before my XJ was lifted....