This allows you to use the built-in secondary sidebar as an alternate on one sidebar themes (you'll want to register a separate sidebar if you are using two sidebars in your theme layouts). This has a limited scope, I would recommend a plugin like Display Widgets if you are going to have a more complicated page-by-page application.
|* Place this into your functions file|
|unregister_sidebar( 'sidebar-alt' );|
|'id' => 'sidebar-alt',|
|'name' => 'Alternate Sidebar',|
|'description' => 'This sidebar will appear instead of the primary sidebar, when the alternate sidebar page template is used.',|