Quote fromI make a lot of purchases at Amazon.co.uk and, less often, at .com. I have my card attached to my account so it's already available to make an Honor System donation. I guess you can start here for more info.
So, if I read that right, I chuck $25US at Amazon, ~$23.99US gets kicked to the website. Seems pretty straight-forward to setup. I didn't go through it enough to see what kind of linking you can do (if any) between payer and forum ID to be built into the WAU to nix the spam but, hell, it beats PayPal just as a donation route.