Good question, Cynthia.
There are many places that make children's artwork archival and ready for framing. We like The Kinder Studio because they offer a lot of choices, you can get your child's work framed and matted or even made into greeting cards, and the prices are reasonable. You can either e-mail a JPG or mail the original and The Kinder Studio will photograph the piece, scan it and print it onto canvas.
Have you done something like this with your child's artwork? Who can you recommend?