Here's an idea that I'm sure we'll see popping up on shortlists at Cannes Titanium during the Lions Festival. Pay with a tweet takes the 'link economy' thought one step further and allows tweet-payers to download copies of a book, a song or whatever you can make downloadable, paid for by tweeting it. The tweet-payer passes on the message that the book is available, and the followers who read it might also pay with a tweet, kickstarting a viral spread of said item.
It’s simple, every time somebody pays with a tweet, he or she tells all their friends about the product. Boom.
RGA came up with the idea to promote the book "Oh My God What Happened And What Should I Do", but soon the system took on a life on its own and it can now be seen a link-currency on music sites and promoting other digital books.
Now, if we can just get the supermarkets and my landlord on the link-currency chain accepting this tweetpayment, I'll be set!