Google Page Creator Example
What is in orange in this page actually comes from some other 'included' pages.
Before the inclusion/inlining occured this page had a link to page inner and the 'text to display' associated to that link was set to the special value httpsubst. As a result, after inlining, this page now includes content from the inner page, right there:
The navigation bar was also a similar include, from the navbar page. The side bar comes from page sidebar. The footer at the bottom of this page comes from the footer page.
If you compose pages using Google Page Creator and if you want to avoid duplicating the same content over and over again (same side bar, same footer, etc), then you can use httpsubst to compose your pages (re)using content from some other pages.
Download instructions and documentation: http://virteal.com/ClientSideInclude
Please have a look at the HTML source to see how the httpsubst.js file is invoked.