I was an intern at the British Red Cross, earlier this year, working in the Digital Fundraising team to help develop their website. I was thinking about raising money for charity quite a lot, and especially new interesting ways of fundraising digitally
So when I saw this article in RWW I was definitely interested: basically a new service called Help Attack allows you to donate a certain (small) amounts of money each time you tweet (with support for "Facebook and more" coming soon) to charity. Now this is a great idea, but it relies on you to go to Help Attack's website, link it up with your Twitter account, set a donation amount, etc. This is (I think) a bit of pain for the average user - and it means Help Attack has to get the message out about the service.
My solution: charities do a "licensing deal" with Help Attack, so that the charity can put a simple "Sign in with Twitter to donate" button on their website (obviously with an explanation of what it'll do). This will then automatically set it up to donate say 10 pence for every tweet - or however much the charity wants to set. At some point bank details would have to be entered, but maybe you could set up an autotweeter with a link to the relevant site.
I think this'll even be pretty easy to set up for the charity - Help Attack could even build an API to make it more frictionless. I've seen some charities do similar sort of things before - for example using Just Giving as portal for donations.