A million pieces of art will be merged to create a single painting via the internet to raise money for charity.
Holly Johnson is one of the more famous contributors
The One Million Masterpiece website invites people to paint or draw a picture using their mouse.
Each person will be charged £3.50 to contribute - the project hopes to raise £3.5m for charities including Oxfam and Save the Children and Action Aid.
Singer Holly Johnson and playwright Tom Stoppard are among those taking part in the project, which launches on 15 July.
The final giant canvas, measuring 80m by 31m will be unveiled at a major London landmark in July 2007.
Organisers say the canvas will be the largest work of collaborative art produced and will be recognised in the Guinness Book of Records.
"This project is about using the power of the internet to bring people together using a universal language," said One Million Masterpiece artistic director and founder, Paul Fisher.
"This picture will tell one million... personal stories, highlighting both the diversity and similarity of people from around the world," he added.
Contributors can choose which charity their donation is given, with the World Cancer Research Fund and the WWF also set to benefit.
Users have to register and will be given tips on how to create the image they want. They can amend their creation at any time and also view other people's work.