I can't remember losing anything, but I kicked off a pannier containing my laptop which cartwheeled down the road, and survived
Thinkpads ftw.
I also had my route sheet holder positioned so that it unclipped my Smart 1W LED onto the road 3 times before I realised what was happening. Each time the batteries popped out, but it survived.
Somehow I knocked my frame mounted HPX pump off and it got ran over by a car