Math skill tasks for grades K-5.

http://www.bbc.co.uk/bitesize/ks1/maths/
Various math skill games for addition, subtraction, multiplication, division, time, measurement …

http://www.eduplace.com/kids/mw/
Math games that address standards for each grade level

http://www.arcademicskillbuilders.com/
Game for addition, subtraction, multiplication, division, integers, decimals, fractions, ratios, money, time, and algebra)

http://www.free-training-tutorial.com/math-games.html
Math instruction/lessons/games for all math concepts.