chrisguitarguy

Arbitrary Sidebars allows you to add widget areas via an page in the WordPress admin area. What you do with those sidebars on the front end is up to you and your theme.
This plugin requires PHP 5.3+. Please check your server configuration before installing.
Some use case ideas:
<ul>
<li>The end user wants to associate sidebars with individual posts and pages. This plugin ould provide half that functionality: easily creating widget areas.</li>
<li>You need reusable content blocks and want to take advantage of the widget system.</li>
</ul>

Arbitrary Sidebars

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.

Arbitrary Sidebars vs Acquaintsoft sidebar generator