Here are some other resources you can use to learn more about magic squares.
4-by-4 Interactive Magic Square Form (PDF, 30kb)
3-by-3 Interactive Magic Square Form (PDF, 30kb)
Antoine de la Loubere's Method Interactive Sheet (xls, 10kb)
Magic Square Genie (xls, 40kb) - A program in Excel that enables you to create a magic square for any magic sum.
Madachy, J. S. "Magic and Antimagic Squares." Ch. 4 in Madachy's Mathematical Recreations. New York: Dover, pp. 103-113, 1979.
Mathworld - A comprehensive look at magic squares from a mathematical perspective.
Magic Squares - A great site for information about magic squares. Contains lots of mathematical curiosities dealing with magic squares.
Suzanne Alejandre's Magic Squares - Site dedicated to the history of magic squares. This site also contains lessons on magic squares teachers can use in their classrooms.
Illuminations: Magic Squares - NCTM's lesson on magic squares; contains lesson activity sheet.
Grogono's Magic Squares - A site dedicated to magic squares.
Magic Squares, Magic Stars, and Other Patterns - Check this site to learn about magic stars and how they relate to magic squares.
Allmath.com - Games involving magic squares.
The Anti-Magic Square Project - Interesting site about "anti-magic squares". Don't know what they are? Then you need to check this out!