bjplink

Export Comment Authors lets you extract the Names, Email Addresses and more of your Comment Authors into a CSV file. This plugin is a great way to jump start a newsletter by importing the resulting CSV file into any of the popular newsletter services like MailChimp, AWeber or Campaign Monitor. It can also be used to extract information on a per post basis for things like contests.

Export Comment Authors

Export Comment Authors lets you extract the Names, Email Addresses and more of your Comment Authors into a CSV file.

flocsy

Authors Widget shows the list or cloud of the authors, with the number of posts, link to RSS feed next to their name, avatar. It is useful in a multi-author blog, where you want to have the list in the sidemenu. 
The widget can also display an “Author Cloud” if <a href="https://wordpress.org/extend/plugins/seo-tag-cloud/" rel="ugc">SEO Tag Cloud plugin</a> is installed.

Authors Widget

Authors Widget shows the list or cloud of the authors in the sidemenu.

Export Comment Authors vs Authors Widget