What can I do with lingots?
I have too many of them right now. I can't keep wagering them... I wish that I could redeem a bunch of them (along with $14.99 plus shipping and handling) for a t-shirt, to help fund more Duolingo...
There are many uses for lingots :). When you click on the lingot store, you can find all sorts of things to help you get through lessons, keep your streak, or enhance learning. All of these items can be found, and there have been many debates over which new items should be added to the store.
You can give them all to MEEEEE!!! :D
-ahem- Just kidding. The app lets you buy outfits for the Duo owl with your lingots, so that might be one thing to spend them on, but really at the moment there isn't much you can do repeatedly. Having a shirt payed for in lingots would be detrimental to Duo's funds, and having a shirt payed for in money and lingots would be hard on new people or people without many lingots.