antonioandra.de

Enables your blog readers to suggest new post tags or upvote/downvote existing ones. 
Downvoted tags are eventually removed. 
A few more features are on the works as is the expansion of this readme document.
<h3>RoadMap</h3>
Add some frontend feedback; 
Add support for custom taxonomy tagging; 
Synonym dictionary; 
Better documentation, ui and automatic integration.

Author: António Andrade

Enables your blog readers to suggest new post tags or upvote/downvote existing ones.

M A Vinoth Kumar

buffercode

Through this plugin, user can able to combine the repeated tags under the single group tag name
<ul>
<li>Users can able to add repeated tags under a group name</li>
<li>Users can able to add up to Ten custom group name and tags</li>
<li>Users can select the group name in Add New Post section</li>
<li>After publishing the post, all tags under the respective Group name will be added to the tag section.</li>
<li>User can also edit the multiple tag in quick edit</li>
<li>User can also do bulk edit (new)</li>
</ul>
For More information : http://buffercode.com/multiple-tags-wordpress-plugin/

Multiple Tags

Through this plugin, user can able to combine the repeated tags under the single group tag name

Author: António Andrade vs Multiple Tags