I already knew a few uses for eggshells like adding to your compost and feeding them to chickens for calcium intake, but I was quite surprised to see all the things you could actually do with egg shells. To see the full list of all the things you can use your egg shells for check out this excellent article by theprairiehomestead.com. Be sure to let me know if there is something you use them for that they might not have mentioned. Check out the link below.
30+ Things to Do with Eggshells