I've worked with Creative Action Network on several of their crowdsource campaigns. As one of the designers that produce work to be ready for campaign launch. It's been a cool and giving experience. You can see the Recover the Classics entry in my portfolio here on Behance.
This campaign is in co-operation with Global Zero, a movement working for a world without nuclear weapons. For every poster sold 30% of the profit goes to Global Zero's work. Who wants nuclear weapons on our beautiful planet anyhow?
Buy & support here.