Great game for estimating and halving. You can control the range 0-20 0-100

The concept is simple. A foldable number chart is a strip of paper, with blank squares for digits, and next to them, words indicating the value of the digits. The strip can be folded to hide the words. So, for example, 7 hundreds 2 tens 4 ones

TagCrowd is a web application for visualizing word frequencies in any user-supplied text by creating what is popularly known as a tag cloud or text cloud.