Free Math Games

Hit the Button - Multi. Tables, Div. Facts, Num. Bonds
Storm the Castle - Card game, grade 1-3
Domineering - 2 players, uses dominoes
Math Playground - up to middle school, games, puzzles, etc
Multiplication.com - Interactive multiplication games
Fun 4 the Brain - Add. Sub. Mult. Div.
Kids Numbers - Addition through Algebra
A Kids Math - Games and puzzles, younger ages
Toy Theater - Games, younger ages
Learn with Math Games - All ages
Math Slice - All ages, games, also for iphone/android, worksheets too
Dr. Mike's Math - Printable games, through 7th grade