The Canonical Portal Home Page
Jakob Nielson, of the Nielson Norman group, recently sent out an interesting newsletter where he highlighted the similarities in almost every successful portal home page. The image below is a composite of ten portal/intranet home pages where the similarities are striking

The general layout typically works like this:
Top horizontal bar: colored background, 100 pixels tall. Typically used for logo, global navigation (often as tabs), and a search box.
Left column: colored background, 200-250 pixels wide. Typically used for a navigation bar with detailed navigation and/or a contextual list of options for the current intranet subsite.
Middle area: white background, 400-600 pixels wide. Typically features one wide column (or sometimes two skinnier columns) containing a few photos or illustrations, a list of news headlines, and boxes with “portlets” to the most important intranet features and applications.
Right column: white background, 200-250 pixels wide. Typically used for a stacked set of boxes, some with colored contents or pictures.
Jakob makes an interesting point about this conformity by saying that portals tend to solve the same problems, and 5 years of searching for the best way to show it has reached a consensus.