I had my car broken when I was in college twice. The first time, I left the car unlocked, went in the next morning and noticed that all my change was gone and my glove box and middle console were left open. The only thing they got other than my change was a spare key for my car that I had stored in the glove box. Total fail on my part. Surprisingly, they didnt take the car (I assume they figured that if they had a key, they could come back and rummage through it as much as they liked). Since they key worked on the doors, ignition, and trunk, it cost me $500 to get all of the locks re-keyed.
About 9 months after that, my car was broken into again, except this time they smashed the window. Took my binder of CD's, which was about 150 in total. I had most of them backed up, but since most were originals and not copies, it still stung. The thing that really sucked about it is that property you lose in your car as a result of break-ins is covered under renter's / homeowner's insurance, which I didnt have.