Lorna Timbah

This plugin creates a widget to show the top commentators in your WP site. Always go back to the Widget settings after each version update to Save your settings. Demo can be found at http://demo.webgrrrl.net
The Top Commentators Widget plugin is adapted from Show Top Commentators plugin at Personal Financial Advice, this widget is easier to manage via the control form (no need to edit the PHP file); additional options are also available to make it more flexible. Read the FAQ section on how to customize the widget. Read the Changelog as well as http://webgrrrl.net/tags/tcw for the latest news on this widget.
This widget is extensively tested with the following settings: Google Chrome 13.0.782.215 m, PHP 5.2.13, Apache 2.2.15 (Win32), MySQL 5.0.51a, WordPress 3.2.1. Further testing and bug report on this widget is greatly welcomed and appreciated.

Top Commentators Widget

Adds a sidebar widget to show the top commentators in your WP site. Demo: http://demo.webgrrrl.net

Podamibe Nepal

This is a plugin that allows users to upload their own gravatar in the media gallery and displays that image as gravatar instead of grabbing avatar from gravatar.com based on their registered email.
You can also use the default gravatar by disabling custom gravatar.

Podamibe Custom User Gravatar

Replace Gravatar with custom picture in your gallery

Top Commentators Widget vs Podamibe Custom User Gravatar