I remember doing something like this in art class as a child... it's always good to remember that technique is actually rather simple, it's always WHAT you want to create that is the key.

Kumi Yamashita creates mind-blowing shadow artworks.

You're right that the most impressive part is visualizing something that doesn't exist and deciding to create it.

very cool!  and this is something little kids could do too.

I think craft stores sell kits for kids to do variations on this theme.

that is good to know!  what a great idea for an art project.

It is! This guy made some pretty ones: http://home.comcast.net/~johnmcboston/stringart.html

these are much more craft than the art like joyce found, but they do show some other directions you can go!  this guy's taste is more along the lines of where my kids will be thinking!!

Yes, these seem much more possible for mortals to imitate.