Wireframes：User experience design resources

Wireframes serve a central function in the development of a web .They are a key tool in communicating the content and layout of each web page for internal and client reviews as well serving as a blueprint for graphic designers to produce designs and for programmers develop functionality.
further website:
http://www.deyalexander.com/resources/uxd/wireframes.html
http://iainstitute.org/tools/