Apparently there's a new app coming soon called LeftoverSwap that allows you to upload a picture of your leftovers as you leave a restaurant and other people near you can let you know that they'd be willing to take those things off your hand.
Ewwwwwwwwwwwwwwww. WHO eats a complete stranger's leftovers!?!?
It hasn't come up yet but if you go to their website here you can sign up for when it comes out.