Haven't left anything behind since I've had the DSLR; I used to set my Canon Powershots down all the time and then realize 15 minutes later I'd left them behind somewhere--did that about a dozen times on a trip to Disney World several years back, but every single time the camera was either right where I'd left it, or had been turned in to an employee.
But one Thanksgiving, I took it with me to our big family gathering at my cousin's house. I am, to this day, certain that I put it in a particular bag just before I left. The bag made it home with me, the camera did not. I never did find out what happened to it; my sister (who lives in the basement apartment on my cousin's farm) and my cousin looked around the house and yard but never found it, and it wasn't in anything that came home with me.
I was actually kinda glad, but it gave me the rationale to buy a new camera; just bought a newer Powershot, but it was way nicer than the one I lost.
My sister just recently left her camera bag sitting in the parking lot at her doctor's office. She drives a little Miata, and so in trying to fit something into the trunk (which she pretty much keeps stuffed to the gills), she pulled the camera bag out and set it down, planning to put it in the passenger seat instead. Finished re-arranging the trunk, closed it, got in the little car and drove off. Miraculously, she did not run over the bag (nor did anyone else) and someone from her doctor's office saw it almost immediately, brought it inside and called her to see if it was hers, (knowing she'd just left and that she did photography). Prompted me to put my contact information in my bag, just in case it ever gets separated from me and happens to get found by someone honest.
Also--not camera gear, but related equipment: I ran over a laptop and an external hard drive (at the same time). I was in intense pain about 2 a.m. one night and thought maybe I had appendicitis or kidney stones. So I decided to go to the ER (and yes, I was gonna drive myself even in pain, because I live alone and I'm bullheaded and not always that bright...and don't really think well at 2 a.m.). Knowing it could take hours, I grabbed my laptop bag to take with me. Got out to the car, put stuff in the trunk, then suddenly thought of something else I needed--never realized that I hadn't ever gotten the laptop case into the trunk, even when I first felt the car run over it--actually, I thought I'd just gotten a flat tire...so I pulled FORWARD, back up into the drive (and by so doing, running over the laptop case AGAIN, just for good measure) and got out to look at the tire. Amazingly, I was able to extract most of the data off the laptop's hard drive, even though the laptop was pretty mangled looking. The external drive had one tiny, tiny little dent on the outside case, but I've never been able to pull a thing off of it.
