Nam-ho Park an information architect in Virginia has a great article on using wireframes.
“Wireframes serve a central function in communicating the content and layout of each web page for internal discussion and client review as well as a blueprint from which graphic designers and web developers will derive final designs. It’s importance, roles and implementations are discussed in this article.“
As well Omni Group produces a wonderful piece of software called Omni Graffle which when used with Michael Angeles’ palette becomes a fantastic tool for producing wireframes. If you purchased a new Macintosh recently and are using OSX on more than a casual basis you may have noticed that this application is included in the software installation for free.