I went backpacking this weekend with a friend of mine, up to Rachel Lake near Snoqualmie Pass. When we got there we noticed a couple of cars with broken glass in the parking lot. Stupidly we didn't consider it very much.
When we got back to the car on Sunday we found the windows intact but that it had been rifled through. It looked like I had lost a bunch of CDs, and she had lost her purse, but she hadn't left anything in it. So, not disastrous.
Until she got home and realized her keys had been in the purse. And the thieves had used the key to break into her apartment. They made off with her computer, some electronics, jewelry, checks, credit cards... they withdrew $1000 dollars from an ATM down the street... I later realized that I had stupidly left my passport in the car...
Obviously, the moral is something you know already: don't leave anything of value in your car. I am still stunned by the persistence and industriousness of these fuckers, that they'd break into multiple cars at the same trailhead two nights in a row.