At Least 10 Uses for Egg Shells

From ThriftyFun.com

Pest Control
I use finely crushed eggshells around seedlings that I transplant into my garden each spring. The shells keep snails, slugs and cut worms away. Apparently, the shells are abrasive to these critters and they won't crawl over them to eat the young plants.
By Readingiggits

Add Calcium To The Soil
I've heard that tomatoes love them, something about the added calcium in the soil. So when I planted mine this year, I crushed up a bunch of eggshells and mixed them in around the plants.
By Beth - MA

Seed Starter
You can also use them to start seedlings in. Then when you transplant, just crack the shell and plant the whole thing. Of course this only works for small seedlings.
By Diwitch

Eggshell Seed-Starting Pots
To make eggshell seed-starting pots: Crack the tips off several eggshells, reserving the eggs for cooking. Fill shells with a light soil mixture and one or two seeds (nasturtiums were used in the book), and prick drainage holes in the bottom of each shell with a pin. Keep moist and warm. When seedlings have reached a suitable size, plant them directly in the ground, crushing the shell so the roots can emerge.
By Mythi

Deer Deterrent
If you have deer eating any of your garden plants, throw the eggshells out there because deer HATE eggs! Otherwise, they are good for your plants, anyway. Just crush and use in your potting soil or mulch.
By Margie

Compost And Mix With Birdseed
I crush them up very fine, and put them in my compost tumbler. On occasion, I dump them on the ground in the area where I feed the birds. The birds need grit in their gizzard to help digest food, so they eat the shells.
By Harlean from Arkansas

Make Sidewalk Chalk
Sidewalk chalk! Here's a great link to making the chalk, however after I washed the shells and let them dry, I ground them up in the blender rather than on a rock - much easier!
http://www.make-stuff.com/kids/eggshell_chalk.html
By Vinnyswoman

Bedtime Tea
Bedtime tea, you wash them, then bake them until brown. Crush and boil as you would tea. Stain and make tea as you normally would. Enjoy a cup before you go to bed, as told me by my grandmother.
By Susanv

Snail Food
Egg shells make good food for pet snails. They need calcium in their diet to maintain their shells.
By Sylvia

What the Egg Industry in GA is trying to do:
http://www.whistle.gatech.edu/archives/05/oct/24/eggwaste.shtml

Here in the NE US, eggshells for songbirds is very important. While much of the NE has worked very hard to reduce acid rain, neighboring states haven't been so diligent. The acid rain leaches calcium out of the soil, making calicum rich insects scarce.
This is just one theory of why the Wood Thrush has declined so severely in the last several years.
Anecdotally, I have been putting out ground eggshells for "my" birds for 3 years. Their populations have grown, the variety has significantly increased - with 3 new species a year showing up in my backyard (do a search on the Great North American Backyard Bird Count). I even have the reclusive Wood Thrush and Pileated Woodpecker coming in for supplementation.

If you want to do more for your soil, your birds and your landfills, consider asking your favorite restaurant to save their eggshells for you to use. You'll need to rinse them thoroughly. I bake them @ 200 for 20 minutes before I grind them up in either the blender or with a mortar/pestle.

I scatter them over my daffodil bulbs all times of year, in my veggie garden and even in my grass. All plant life needs calcium to help it through drought and severe weather changes. They also need it for strong root development.

It's been a long time since I put them in my compost. I just take them straight to the needed areas and let them do their work in place. Believe it or not - earthworms appreciate them as much as any other bird food "on the hoof".

L