pflonk

This plugin allows you to pass content to any sidebar from the page without using userdefined fields. Therefore it is possible to use the WYSIWIG-editor of your choice.
How it works: 
This plugin comes with a new enclosing shortcode [sidebar_content][/sidebar_content] where you can place any content, you want to have displayed in the sidebar. You will be able to use other shortcodes within this shortcode to use galleries, videos or any other stuff in the sidebar of your choice.
Additionally there will be a new widget which you can insert into the sidebar you want to have the content displayed. 
If you would like to pass content to an existing sidebar, there is another possibility using the [insert_sidebar_content] shortcode in any place you want. You are able to pass an id and/or a class to that content, to be able to style it with css as you like. This happens by simply adding: 
[insert_sidebar_content id=”yourID” class=”yourClass”] to the shortcode. You can of course use just one or none of them. If you do not specify any custom class or id, there will be a standard class and id called “insert_scfs” applied to the content, wrapped in a div.
<h3>Features</h3>
<ol>
<li>Widget</li>
</ol>
<ul>
<li>optional title (if empty, no tag will be generated)</li>
<li>optional title tag (default h3)</li>
<li>optional title tag CSS-classes</li>
<li>optional content-wrapper tag (default div)</li>
<li>optional CSS-classes for content-wrapper tag</li>
<li>optional CSS-id for content-wrapper tag</li>
<li>default values for every of the above possibilities</li>
</ul>
<ol>
<li>Shortcodes</li>
</ol>
2.1 Content-Enclosement
<ul>
<li>[sidebar_content]CONTENT[/sidebar_content] for use on any page</li>
</ul>
2.2 Widget-Display
<ul>
<li>[insert_sidebar_content id=”yourID” class=”yourClass”] to display the content from the [sidebar_content]-Shortcode in any widget you like</li>
<li>applicable id and classes</li>
</ul>
You will find further support on http://dev.offensichtlich.net
<h3>Thanks</h3>
Thanks to the authors that provided information about how to implement this simple little function that I just put together:
Ryan Bosinger 
http://www.ryanbosinger.com/boztown/2013/03/07/wordpress-custom-content/
1st-tec.de 
http://www.tipps.1st-tec.de/wordpress/39-wordpress/sidebar-widgets/152-eigene-widgets-fuer-die-sidebar-erstellen.html

Sidebar-Content from Shortcode

This Plugin enables passing content to any sidebar from the page without using userdefined fields. Therefore it is possible to use the WYSIWIG-editor  …

WebFactory

Manage and replace sidebars and other classic widget areas on your site with Custom Sidebars, a flexible widget area manager.
Make custom sidebar configurations and be able to choose what classic widgets display on each page or post of your site.
<ul>
<li>Need to make a widget sticky or fixed? Try our free <a href="https://wordpress.org/plugins/sticky-menu-or-anything-on-scroll/" rel="ugc">WP Sticky Anything</a> plugin.</li>
</ul>
Custom Sidebars works ONLY with the classic widgets screen that was used in WordPress before version 5.8. If you want to use it with version 5.8 (and above) you have to install the official <a href="https://wordpress.org/plugins/classic-widgets/" rel="ugc">Classic Widgets</a> plugin, or enable the classic widgets interface yourself. Once the classic widgets screen is activated the plugin will work the same as before.
<ul>
<li>Having problems setting up SSL or generating an SSL certificate? Install the free <a href="https://wordpress.org/plugins/wp-force-ssl/" rel="ugc">WP Force SSL</a> plugin.</li>
</ul>
<h4>Display Different Sidebars on Pages and Posts</h4>
Custom Sidebars allows you to dynamically display custom widget configurations on any page, post, category, post type, or archive page.
★★★★★
<blockquote>
“Custom Sidebars will go on my “essential plugins” list from now on. I am pleased by how easy it was to figure out and by how many options are available in the free version.” – <a href="https://profiles.wordpress.org/monkeyhateclean" rel="nofollow ugc">monkeyhateclean</a>
</blockquote>
★★★★★
<blockquote>
“This plugin does exactly what it says. It’s light, integrates well into WordPress and gives you tons of possibilities.” – <a href="https://profiles.wordpress.org/darknova11" rel="nofollow ugc">DarkNova</a>
</blockquote>
Every part of Custom Sidebars integrates seamlessly with the Widgets menu for simplicity and control. No confusing settings pages or added menu items, just simple core integration.
<h4>A Simple Flexible Sidebar Manager</h4>
** Custom Sidebars Includes: ** 
* Unlimited custom widget configurations 
* Set custom widgets for individual posts and pages, categories, post types, and archives 
* Seamless integration with the WordPress Widgets menu 
* Works with well-coded themes and doesn’t slow down your site 
* Set individual widget visibility – for guests, by user role, by post type, for special pages or categories 
* Author specific sidebars – display a custom sidebar for each of your authors 
* Clone and sync widget settings – quickly edit complex configurations 
* Import and export custom sidebars – backup and share sidebars
Install Custom Sidebars and see for yourself why it’s the most popular widget extension plugin available for WordPress with over 200,000 active installs.
<h3>Contact and Credits</h3>
Original development completed by <a href="http://marquex.es/" rel="nofollow ugc">Javier Marquez</a>.

Custom Sidebars – Dynamic Sidebar Classic Widget Area Manager

Flexible sidebars for custom classic widget configurations on any page or post. Create custom sidebars with ease!

Sidebar-Content from Shortcode vs Custom Sidebars – Dynamic Sidebar Classic Widget Area Manager