I was shocked by how well leaves come out on a flatbed scanner!  For children who are interested in the computer, this is a great way to create an autumn project with them.  Just lay the leaves on the glass, close the cover, click scan and you're done.  

You can even use your image editor to fade the leaves and create neat backgrounds like the one on this page (it's a faded scan of the leaf Tasha got from her teacher).