Using what seems to be a unique algorithm to identify and track eggs, Talking Augmented Easter Egg enables iPhone and iPad users to virtually decorate plain white eggs, poke them until they (again, virtually) break and even talk to them. People may think you are crazy, pulling an egg from the refrigerator, looking at it through your iPhone and then starting to talk to it, so maybe you should let your kids play with this one.
When I tested the application on my iPhone 3GS, it surprisingly worked well. The tracking was a bit jumpy (as you might expect), but it did identify my "test egg", even with a few decoys around (like a white charger). True, it's a gimmick, that will lose its attraction in a few weeks (unless you are an angry bird, using the app to track your stolen eggs), but it's probably make your kids quite happy for those few days.
More details can be found on Irregular Apps' website.