Have you ever tried painting blown eggs?
They are surprisingly easy to blow. Take a normal egg, make a small hole at the top and bottom of the egg with a sharp needle, and blow the egg white and yolk out of the shell (the yolk is often the hardest bit) This will leave you with just the shell, which will last for years!
I've found the best paint to use is Making Memories Scrapbook Colours...and if you're like me, you will have lots of these on hand (and using them also helps ease the guilt which goes with having so many!) Blowing your eggs on Good Friday is perfect, because you can use them to make a meat-free omelette ;)
We took our eggs to a friends' house yesterday, and they were just as excited as us, and painted some beautiful designs.