http://www.mathplayground.com/area_perimeter.html
http://www.mathplayground.com/PartyDesigner/PartyDesigner.html
http://www.funbrain.com/poly/
http://mrnussbaum.com/zoo/
http://www.sheppardsoftware.com/mathgames/geometry/shapeshoot/PerimeterShapesShoot.htm
http://www.sheppardsoftware.com/mathgames/geometry/shapeshoot/AreaShapesShoot.htm