I am reminded of the song by the title above every time I crush eggshells. Yes, I do crush them often, thank you for asking. I read in a book last year (The Farmer's Wife Guide to growing a great garden--and eating from it, too! by Barbara Doyen) that crushed eggshells are very nutritional and useful for your soil. Because we go through eggs fast, I thought I'd see. The Farmer's Wife advises you to rinse them and store them in a bucket under the sink until you have a few and then crush and sprinkle them in your garden. Wikipedia says that bird eggshells are about 95% calcium held together by a protein. The crushed shells keep slugs and snails away like pellets do, but for free. They also provide these nutrients for your soil as they break down. Some people use a food processor, I just dump them in a bucket and crunch with a hand rake. I also think it makes my dirt look pretty. Don't you?
(Last year, I bought two strawberry plants on clearance because the season was over. I didn't get any berries, but they spread like mad. After I dug and transplanted, I have 30 plants from two!)
Fun for the kids: start seeds in an eggshell.