I recently came across this donation site, Free Rice, it works through the United Nations, through the United Nations World Food Program, and is totally free to you, they get their money from advertisement as you play the game.
The game is simple, you are presented with a word and four possible meanings for it; click on the correct one, and you donate 20 grains of rice (doesn't seem like a lot, but every grain of rice adds up - the time I looked at it while writing this, 281 million grains of rice were donated the previous day). If you get it right, you get a harder word, if you get it wrong, you get an easier word. Get three words correct in a row, and you get to the next Vocabulary Level (there are 50 in all).
Learn some new Vocabulary. Impress your friends and colleagues. Donate some rice. All good.