Fruit Splat/Place Value Decimals: This game is great practice for thinking about place value in decimals and for adding using mental math. It's designed to have several different levels, and you can play in timed mode or "relaxed" mode.
Flower Power: put decimals in order of size -- a nice complicated game (read the directions)
Balloon Pop Decimals Level 1 and Balloon Pop Decimals Level 2: Pop the balloons from smallest decimal to largest. If a balloon won't pop, it's because you haven't found the smallest. Score is based on time, but you can ignore it if you want and still get the practice.
Math You Can See page
To explore math in art, nature, patterns, society, and more, go to my page called Math You Can See and go to any of the links there. (If you find any that don't work any more, please let me know.)