I couldn't possibly compile a list; there are way too many contributions over the last 5 decades. However, the remarkable ones like watches, expensive sun glasses, and keys are the ones I kick my own arse for, and hopefully do not repeat too often. For me the most disheartening one is a good waterproof light that is on, dropped at night. You watch it sink and know that it will sit on the bottom, a forlorn beacon begging for retrieval, for days and more importantly nights, until the batteries fail. So sad.