Here is a cool little gadget I'd never heard of before. It's a temperature datalogger. It lasts 60 days. Sadly I think it may be disposable (but I'd imagine rechargeable versions exist. )
Suppose you are shipping fruit across the country and you've paid extra to have the trucks chilled down to 65F. How do you know they didn't ship them at 75F and only lower the temp fully just before arrival?
Hide this bad boy in your shipment, then check the USB for data on arrival.