There's a screen called "Golden Eggs" in the game that has 7 icons in it... when you click the icons, it shows a picture of a golden egg with the icon. Anyone know what's going on here?
In different levels (or in special screens) there are "hidden" golden eggs. Once you touch or see them, they will be displayed in the "Golden Eggs" screen. When you touch them there you can play an extra level
Examples on where to find golden eggs:
Make a search on Youtube for "Golden Egg Location", there are many videos showing the exact locations for each of them.
EDIT: This may also be a duplicate of http://gaming.stackexchange.com/questions/4036/how-do-you-get-the-golden-eggs-in-angry-birds :)