galaxiusmons

This allows you to quickly create a unique sidebar for any post, page, category page or for all posts belonging to a category. You simply enter a name for the sidebar when you create or edit a post, page or category. Browse to Appearance -> Widgets, find your new sidebar and add some widgets to it.

Galaxius Custom Sidebars

Allows quick creation of unique sidebars for posts, pages and categories.

itcoderr

This plugin gives you a way to choose what widgets display on each page/post of your website. The plugin’s custom sidebars provides a way, using that you can display custom widget configurations on any page, post, post type, or archive page.
Features
<ul>
<li>Unlimited custom widget configurations</li>
<li>Custom widget for individual post, page etc..</li>
<li>Sorting sidebar</li>
<li>Many more</li>
</ul>

Acquaintsoft sidebar generator

Create custom widget configurations for every page/post on your website.

Galaxius Custom Sidebars vs Acquaintsoft sidebar generator