Curve Stitching
Curve stitching (http://www.ams.org/samplings/curve-stitching and http://britton.disted.camosun.bc.ca/string_art/jbstringart.html) show some connection of math and art. They also tie in a bit with the Pythagorean Theorem, as the proof given at http://www.mathsisfun.com/geometry/pythagorean-theorem-proof.html can be drawn fairly easily using this worksheet.
You can vary the number of sides in the polygon and the number of points on each side. Then you can draw in line segments between the points to show the type of curve stitching figures that can be created.