The kids cashed in their savings bonds last year when I bought my first apartment building - and they invested their money in the building. Based on their informal surveys, they're the only kids in the school that own an apartment building. :)
What a great head start this is for them. They're learning about investing, about compound interest (because we won't let them take their earnings and run!) and they're learning about delayed gratification.
And they get to tell everyone they own an apartment building. Heck - most adults can't even say that! LOL