If you have a few minutes spare, help donate rice to the hungry people of the world AND improve your vocabulary by going to FreeRice.com.
For every word you get right, 10 grains of rice are donated throught the UN to help end world hunger.
According to their FAQ, when you play the game, advertisements appear on the bottom of your screen. The money generated by these advertisements is then used to buy rice. So by playing, you generate the money that pays for the rice which is distributed via the United Nations World Food Program to those in need.
A much better use of time than playing solitaire in the spare moments which exist between working, sleeping and mumsnetting!