I see what you're saying, but I think that if you scale this to a large number of users (especially if the free "thing" is publicly visible), then you're going to have a lot of people abusing it and/or making a mockery of it.  After all, this is the internet, and nearly every community has a subsection of immature/abusive people.<p>To really make it special and encourage people to give, there has to be an element of rarity (or real value).<p>I'm certain that the above approach is valid and would raise money, but I don't think it's going to maximize the amount of money collected for the organization.  I'd estimate that a complete solution could bring in at least two times as many donations, and maximizing donations is the goal here (otherwise I could just do something simple like putting a banner on the front page).<p>Regarding the honor system and scalability: I don't think that there would be much abuse if people had to contact me personally to say that they donated money, but people would be less honest in clicking a button (I imagine lots of people would click it because they planned to give in the future and then forget to do so, for example).<p>Or maybe I'm just entirely lacking faith in the kindness of others and should be more trusting :)