Yep. This is a great reminder why we should all donate to EFF [and that I haven't renewed my membership since a few months ago]
Edit: membership now renewed
Edit: membership now renewed
It's the "Give % of sales to non-profit of your choice" option in Amazon.
That's the reason I've not started using it. Online stores use all kinds of indicators (user agent, OS, number of searches for similar items, etc) to jack up prices when they think they can get away with it, and I suspect this metric is very relevant in that context.
I just donate to EFF and others directly.