Came across this gem on Amazon tonight. Check the reviews and the customer questions and answers, such as:
I will keep this short and simple. I bought this darn thing to help me out because I have been doing this manually for years. I have a spreadsheet and a sharpie. When an egg comes home from the store I create a new row in the spreadsheet, then write the number on the egg. Then I place the egg in the tray and go back to the spreadsheet to update the row. So many times I forgot which egg went in which hole, until I started putting the numbers on the top of the eggs. Then a friend conveniently bought this for me.