The Divisions Plugin enables you to create parts, called divisions, of your
web page with an individual look and feel as determined by individual sidebars,
navigation menus and header images. At the same time, all divisions share the
same content data and a single posts can be displayed in any division.
Navigation menu entries are used to switch between divisions. Technically, the
division is determined by an additional argument in the URL.
Screenshots

Overview of divisions in your web page.

Edit screen for a division: Choose which navigation menus and sidebars to replace and decide whether the division should replace the header image in your theme.

Replaced sidebars are populated with widgets just as the normal ones in the widgets screen of the Appearance settings.

Menu items can be configured such as to modify the current division.

Replaced navigation menu locations are populated with menu instances just as normal locations.