I also saw one time on FN that if you put the egg in a glass of water you can tell if it is spoiled or not. I can't remember which one is spoiled, but the egg will float or sink. Maybe someone here will remember.
Eggs have a much longer shelf life when stored under refrigeration, I have read somewhere that for every day or so the eggs out kept out of refrigeration, they age the equivalent of a number of days kept in the fridge.
As people have mentioned, fill a glass up with water, whack an egg in there and if it rises, turf it. I have used eggs well passed the date on package (kept under refrigeration as well though) by testing if they were OK first.