The German computer magazine c't reports in their issue of the week of April 1 that since ink jet ink is more expensive than silver, that you can pay small amounts by having your printer fill a page with black ink, and the printer producers will send the money they will get back from you when you refill on to whomever you wanted. The protocol is called PPP, Picopayment Protocol.
It is such a crazy idea, the printer industry might actually try it. But I am calling this an April Fool's joke, c't usually has whoppers. Let the crazy day 2009 begin!