Miro includes a Firefox add-on that sends referral fees via Amazon
The Miro video player is open-source and built by a non-profit and during its install includes I Heart Miro which is a simple Firefox extension that gives a referral fee to the Miro organization when you shop at Amazon. You'll never notice it, it doesn't cost you a thing, and it's easy to uninstall at any time.
I wonder if there are any other Firefox add-ons that do the same - but dont tell you they are doing it !