I'm sure everyone has experienced feature and scope creep and all the knots in the stomach associated with them. This is a great book (also available in pdf) from the Newfangled Web Factory guys.

http://www.newfangled.com/client_vs_developer_wars (direct PDF link)

We wrote Client vs. Developer Wars after discovering how radically grayscreen prototyping changed the dynamics of the web development process. Grayscreen prototyping (building a simple HTML model of a website) provides an extremely effective way of communicating a website's content, structure, and functionality before design and programming begin. Prototyping overcomes many other difficulties commonly associated with web development, such as managing expectations, communicating effectively, working through the design process, and creating and delivering content.