I've had my wallet stolen (at ASU, when it was stashed in my briefcase under my desk when I was a TA) and it was returned, but only after I had replaced everything. What a pain. They saw my faculty ID and returned it to the department office. I've never lost anything, though.
I keep my small bike sized wallet in my purse, which is kept under the front seat of my locked car (I have a station wagon, so no trunk), when I go in to see clients at their homes or schools. I bring my work bag in with me, where I have my cell phone, glasses, and a couple of bucks. I don't take my wallet into my office, either. I used to take my purse in with me to clients, and then, about a year ago, I *think* I had some money stolen. I say think, because I couldn't remember how much cash I had. I rarely use cash for anything, and when I get it, it's usually a good amount, so I don't have to go to the ATM too often. I also keep my car key, the electronic kind, either in a zipped pocket in a coat, or in the same exact spot in my work bag or purse. I am obsessive about checking to see that I have it before exiting my car, as it's not the kind of key that can go on a chain.