srcoley

This wigetized plugin shows the gravatar and info of the most recently active authors of your blog. The author with the most recent post will be displayed first, the author with the second latest will be displayed second, and so on.
Awesome Authors allows you to select ‘Sticky Authors.’ These authors will be displayed at the front of the list no matter how long ago their latest post was published. Conversely, you can select authors to be ‘Excluded Authors.’ These authors will never be displayed in the list no matter how many posts they have or how recently their last post was published. You can also set a minimum post requirement. If you set this to, let’s say 10, then only authors with 10 or more published posts will be displayed on the Author Bar. Some of the other options include gravatar display size, and how many authors overall to display.

Awesome Authors

This wigetized plugin shows the gravatar and info of the most recently active authors of your blog.

Stanko Metodiev

This plugin will give you a simple widget that you can use to display your blog’s authors, including their gravatars and post counts.
The widget uses universal widget styling, so should fit perfectly into any WordPress theme.
Features
<ol>
<li>Blog Authors Widget</li>
<li>Widget Title Option</li>
<li>Option to enable author gravatars</li>
<li>Option to enable author post counts</li>
</ol>

Simple Blog Authors Widget

This plugin lets provides a simple widget to list your blog's authors, including gravatar and post counts

Awesome Authors vs Simple Blog Authors Widget