Create custom sidebars (widget areas) and replace any existing sidebar so you can display relevant content on different pages.
Create and display custom sidebars according to the content being viewed.
Artisteer Custom Sidebar Generator can create as many sidebars as you need. Specify a sidebar using the new sidebar shortcode.
Sidebar Generator Generates as many sidebars as you need. Specify a sidebar on a per-page/per-post basis. Now supports themes with multiple sidebars.