I donate to http://www.worldcommunitygrid.org/ when possible. Right now I'm donating my monthly $100 MSDN Azure credit. I would do more through AWS but I don't have the budget to do so at the moment.
It's $233.89 according to that Amazon link, the $385 is crossed out.
Edit: The price has dramatically changed since both of us viewed the page. My comment is no longer valid. The current 7:50AM PST 10/8/13 price is $279.99.
