I have previously written about Hot Seat, which is a game I sometimes use to review before math tests. For some quick, non-content related games, I sometimes use some of the following sites:
Math Playground – There are some content based games for lower grades, but I like the Logic Games section of the website.
Terry Stickels – Terry has written many puzzle books, but there are also an assortment of puzzles on his website.
Pencil ‘n Paper Puzzles – There are a wide variety of puzzles on this site … love this site.
Erich’s Puzzle Palace – Another good site with a wide variety of puzzles.
KrazyDad – This is my favourite site for printable Sudoku’s, Kakuro’s, and other similar games.
Have fun playing!