Forget counting friends and posting flattering pictures of yourself on Facebook – if you've got a bit of time to kill and want to make yourself feel good in a way that is actually useful to the future of civilisation, then check out this brilliant website.

The idea is simple. Test your wits on a multiple choice vocabulary quiz, and every time you choose the right word, 10 grains of rice are donated to the United Nations World Food Program (made possible by corporate sponsors like iTunes and American Express). Clever dicks that us humans are, it's only natural that most people want to see how smart they are and how far they can get – behaviour that the site brilliantly harnesses into meaningful charity (before you know, it you've donated half a bowl of rice). It's clearly working; from its launch date on 7 October 2007 (830 grains donated), the site has now donated 1,330,639,890 grains of rice to the programme.

But it's not just about the charity. The site also aims to improve vocabulary, helping people to formulate their ideas better to enhance speaking and writing skills, as well as grades, job performance and respect from peers. FreeRice has a custom database containing thousands of words at varying degrees of difficulty. There are words appropriate for people just learning English and words that will challenge the most scholarly professors. In between are thousands of words for students, business people, homemakers, doctors, truck drivers, retired people… everyone!

Pure genius. Give it a go now – www.freerice.com – and spread the word.