There are two types of Easter Eggs, one is a specially decorated egg given to people on the occasion of Easter and the other type is basically a intentional hidden message or joke or feature in a computer program, website or video game.
Many popular websites like Google, Yahoo and even quite a few small websites and services hide Easter eggs somewhere on their applications, services or websites, these though are not easy to spot.
However a website called Easter Egg Archive collects and stores all the Easter eggs, making it easier to find them in one place.
The website tells users about the Easter Eggs and the exact steps to replicate to find the Easter eggs.
If you have some time in hand, do visit the website and browse and search for Easter Eggs in your favorite applications or service and fun with it.