The Future of Political Funding?

I've read a lot of analysis of why Barack Obama won last week's presidential election, and a lot of his success is put down to the way he managed to raise money from individual voters, rather than corporations. A lot of his campaign's activities in social media (Facebook pages, YouTube channels etc) were to recruit grassroots support and ask for donations. This meant that the Obama campaign was able to spend more money than the McCain campaign, and that the way he used the money was less restricted than if he had received larger amounts from a few corporate donors.

I also read the story about the Atheist Bus campaign in the UK. This campaign, in response to a pro-Christian bus campaign, raised money from individuals via the JustGiving charity site, to put a pro-atheist ad on one London bus. As it's turned out, the slogan ("There's probably no God. Now stop worrying and enjoy your life") caught the public's imagination so much that they exceeded their target within hours, and now, with nearly £120,000 in donations, the organisers plan to make the campaign national. The average donation is just over £10; over 800 people have donated (the charity can can claim the tax on the donation back if the donation comes from a UK taxpayer). The campaign is now also selling t-shirts with the slogan.

So why not do something like this for political campaigns? Ask people to design a slogan or a poster (heavily moderate this of course), set up a vote to select the best, and then raise money with the specific aim of running that poster. This way parties would raise money for campaigns (remember that many political posters only appear in one place, but generate lots of PR coverage), and could engage their supporters in a tangible way.

I expect that this will be done to some extent during the next British general election; can you imagine how many would have been willing to donate a tenner to see something like a 'Bliar' poster run across the country a few years ago?