http://math.rice.edu/~lanius/frac Fractals.  (5/6+) This site has great upper elementary and middle school units on the mathematics of these visually stunning images.  This site also include Internet research activities.

http://sprott.physics.wisc.edu/fractals.htm Sprott’s Fractal Gallery. (6-12) INTERACTIVE  This site is from Julien C. Sprott.  It includes an archive of previous fractals and links to a large number of fractal patterns from other sources.  Every day the site present a new fractal that is automatically generated.