As a programmer the saying "A picture says more then a thousand words" often feels like a fallacy but Ricky Ho has a history of illustrating his points beautifully. His nosql patterns post is another very good read: <a href="http://horicky.blogspot.com/2009/11/nosql-patterns.html" rel="nofollow">http://horicky.blogspot.com/2009/11/nosql-patterns.html</a>