I remember visiting this website once...
It was called Answer4Earth - Test your knowledge. Save the Earth.
Here's some stuff I remembered seeing:
Every answer you give helps plant a tree: 1 answer =
Option: Create an ID to track your scores, and how many trees you\'ve personally brought to life.
WARNING: Playing this game may improve the Earth\'s environment. Also heavy risk of increased personal intelligence.
Next question difficulty level depends on your overall skill.
Each correct answer you give generates a donation to plant trees, helping our environment in countless ways! Details