Thinking Required

http://www.sheppardsoftware.com/mathgames/arithmetic/arithmetic.htm

Add Like Mad

http://www.sheppardsoftware.com/mathgames/Add%20Like%20Mad%20Math/AddLikeMad_easy.htm

Math Dictionaries

http://users.erols.com/bram/dictionary2.html
http://www.mathsisfun.com/definitions/index.html
http://www.coolmath.com/reference/online-math-dictionary.html
I advise my students to listen carefully the moment they decide to take no more mathematics courses. They might be able to hear the sound of doors closing

Color Your World With Multiplication

http://www.multiplication.com/flashgames/PattyPaints.htm

Math Multiplication and Ice Cream Cones

http://www.multiplication.com/flashgames/ConeCrazyLevels.htm

Math, Mental Math, and More

http://www.bbc.co.uk/schools/ks2bitesize/maths/number/

http://www.bbc.co.uk/schools/ks2bitesize/maths/shape_space/

Angles, Lines, and Graphs

http://www.bbc.co.uk/schools/ks2bitesize/maths/shape_space/

Math Fact Cafe

http://www.mathfactcafe.com/

Math Attack

http://www.toonuniversity.com/flash.asp?err=503&engine=15