What if it wasn't just celebrities? Perhaps it could be opened up to anyone who wanted to contribute. A book would need to be limited to a certain number of pages. With the power of the web, you could end up with thousands of entries. Place the resulting artwork on the web and let people vote on which pieces make it into the book. The site could be partnered with a print house so that people could order any of the artwork as posters or giclees. Once the book is published, have a big book signing - bringing all of the winning artists together. Sell a limited number of signed books from that signing on eBay. Have a limited group of charities and let dispersement of resulting funds be a part of the voting process.