profpanda

This plugin allows you to create a new widget to your Dashboard, choose the postion of the widget (Core or Side) and even the priority to show your widget at the very top of the list .
Features:
<ol>
<li>Allow to create new widget area to your Dashboard</li>
<li>Support HTML codes (and of course, CSS styles)</li>
<li>You can choose the position of the widget, Core (the left) or Side (the right).</li>
<li>You can mark down the Priority option to make your widget be at the very top of the list on the Core position.</li>
</ol>

ProfPanda Custom Dashboard Widget

This plugin will be usefull for all purposes. And will get better in the next version when it will allow you to create more than one widget areas on Dashboard.

Usefull for all purposes

This plugin allows you to create a new widget to your Dashboard.

Stencies

Stencies allow you to insert pre-formatted and styled (text/images/css/templates/HTML/article structure) from Stencies.com. 
You can either create your own Stencies or insert Stencies created by other Stencies.com or other users.
You do not need to register to use Stencies, but you must register to be able create your own Stencies. Documentation on how to do this will be made available within the next month or two.
The plugin and the Stencies.com website are currently in beta testing phase; any bug reports or suggestions will be highly appreciated.
You have the ability to overwrite/customise the Stencies CSS styles
This plugin works on WordPress multisite
View the short demo.
<iframe loading="lazy" class="youtube-player" width="750" height="422" src="https://www.youtube.com/embed/t275cLrdR70?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe>

Insert pre-styled elements (either from other users or your own) into your Wordpress posts and pages.

ProfPanda Custom Dashboard Widget vs Stencies