brickdots

Assign/Share a todo item to/with internal users by mentioning them.
<ol>
<li>Mention internal users when an admin wants to assign a todo item to colleagues by typing <code>@</code> when creating a todo item.</li>
<li>Mentioned users would get notification emails. A mentioned user would get an email with the todo item and the link to the edit page that the todo list is on. </li>
<li>Check your todo items on the dashboard. All your todo items (todos mention you) will be on your dashboard. You can go to the edit page by clicking an item.</li>
<li>
Create a todo list in many post types
These are the compatible post types.
<ol>
<li>Posts</li>
<li>WooCommerce Products/Orders/Coupons</li>
<li>Event calendar events</li>
<li>More to come</li>
</ol>
</li>
</ol>

Admin Todotastic

Admins can assign or share todo items attached to a post, a WooCommerce order, a product, and a coupon by mentioning internal users.

SherkSpear

This plugin creates Smart ToDo post types, todos are broken into tasks and categorized as Projects. Timers are added on each tasks.
Created Projects as taxonomy for Smart ToDo post types. And each Smart ToDo post types is capable of adding multiple tasks with url references.
Timers are provided on each task and can be controlled with buttons to Start, Pause and setting task as Done. Also edit buttons are provided to edit task description, task url reference and time spent. Proper user’s access are also given to each type of users.
SmartToDos manage page has columns for Projects and Status of the ToDo if it’s Open or already Closed.
Total hours are provided dynamically and Title of window is set to active task with the current time spent. This is inspired from the Task Timer Google Chrome App.
You can email me directly for any plugin request or personal modification such as styles and templates at <a href="mailto:contact@sherkspear.com" rel="nofollow ugc">contact@sherkspear.com</a> or contact me at <a href="http://sherkspear.com/contact" rel="nofollow ugc">http://sherkspear.com/contact</a>
Plugin URI: <a href="http://www.sherkspear.com/portfolio-item/smart-todo-wordpress-plugin/" rel="nofollow ugc">http://www.sherkspear.com/portfolio-item/smart-todo-wordpress-plugin/</a> 
Demo Page: <a href="http://www.sherkspear.com/smart_todo/add-pages-to-sherkspear-for-plugins-as-portfolio/" rel="nofollow ugc">http://www.sherkspear.com/smart_todo/add-pages-to-sherkspear-for-plugins-as-portfolio/</a>
<h3>Detailed Instruction</h3>
After installing the plugin you will find 
Detailed instruction at 
Dashboard-> SmartToDos->How To Use 
 /wp-admin/edit.php?post_type=smart_todo&page=smarttodo_info

Smart ToDo Plugin

This plugin creates Smart ToDo post types, todos are broken into tasks and categorized as Projects. Timers are added on each tasks.

Admin Todotastic vs Smart ToDo Plugin