rockgod100

This plugin creates an area for site admins to jot down post ideas or assign post topics to content authors. Additionally, authors can be given due dates and suggested post types (article, video, etc).
Admins can also e-mail authors directly through the interface using an extension of the wp_mail() function.

Topic Manger

A quick way to remember post topics for single or multi-author blogs

Frank Neumann-Staude

Ulf Schönefeld

polyres

This plugin/add-on requires the plugins FacetWP and Co-Authors Plus (WordPress plugin repository)!
This free plugin/add-on integrates FacetWP with Co-Authors Plus, allowing you to use Co-Author Plus custom fields for front-end search and filtering in a facet. 
With the help of Extend Co-Authors Plus for FacetWP, you can create a lable and choose the data source “co-authors” for your page or post.

Topic Manger vs Extend Co-Authors Plus for FacetWP