These Hide n Squeak Eggs from Tomy were a huge hit with my boys last year. In fact, we only have five left because one was so well hidden we never found it.
It's such a great, versatile toy - you can crack open the eggs to reveal the brightly coloured press-and-cheep chicks, plus it's also a shape sorting game (matching egg bases to the right shaped hole in the box), making it egg-cellent (sorry) for hand to eye coordination and memory skills.
Find one in great condition on Nappy Valley right now.