Area explorer  - perimeter given
http://www.shodor.org/interactivate/activities/perm/index.html

Shape explorer  - no givens
http://www.shodor.org/interactivate/activities/perimeter/index.html

Perimeter explorer – area given
http://www.shodor.org/interactivate/activities/permarea/index.html

Calculate area and/or perimeter – choose difficulty
http://www.funbrain.com/poly/index.html

Angles
http://www.shodor.org/interactivate/activities/angles/index.html

Triangle explorer – area
http://www.shodor.org/interactivate/activities/triangle/index.html

Tessellation – best site!
http://www.shodor.org/interactivate/activities/tessellate/index.html

Surface area and volume – rotate to see all faces
http://www.shodor.org/interactivate/activities/sa_volume/index.html

Structure plans
 http://www.learner.org/teacherslab/math/geometry/space/plotplan/index.html

Shadows
 http://www.learner.org/teacherslab/math/geometry/space/shadows/index.html

Geometric solids
http://illuminations.nctm.org/LessonDetail.aspx?ID=L406

15 Puzzle
http://nlvm.usu.edu/en/nav/grade_g_1.html

Geometric solids and shapes
http://illuminations.nctm.org/LessonDetail.aspx?ID=L406

Space blocks
http://nlvm.usu.edu/en/nav/grade_g_1.html

Sticks and triangles
http://nrich.maths.org/public/viewer.php?rss=1&obj_id=5045?=index

An interesting geometry test
http://www.bbc.co.uk/education/mathsfile/shockwave/games/bathroom.html

PBS Kids Cyberchase has changed. This link will lead you to all their games. Your teacher will direct you which one to click on. 

http://pbskids.org/cyberchase/math-games/