fitztrev

Comment Image Embedder is a very simple plugin that, once installed, lets your visitors add an image to their comments.
It’s rather common for a WordPress user to ask how visitors can embed images in the comments section of their blogs.
This plugin will add a link just below the comment box that a user can click on. When clicked, a prompt will appear for the user to enter the URL of the image. It will then be added to their comment.
Trevor Fitzgerald 
http://trevorfitzgerald.com/

Comment-Images

Comment Image Embedder is a very simple plugin that, once installed, lets your visitors add an image to their comments.

Orangelab

Rickard Westerlind

Dramatically improve the quality of re-sized images by making WordPress use ImageMagick instead of standard GD image library.
Features
<ul>
<li>Preserve embedded color profile in re-sized image</li>
<li>Automatically recognize custom image sizes</li>
<li>Allow regeneration of existing images (optionally for selected image sizes only)</li>
<li>Configure image quality or use dynamically computed default value</li>
<li>Optimize different image sizes for either quality or size</li>
</ul>
Lnguages: English, French, German, Swedish, Turkish
Requires either ImageMagick binary or Imagick PHP module.
<h3>Contribute</h3>
Code repo available on https://github.com/orangelabweb/imagemagick-engine/

ImageMagick Engine

Maybe even better.  It uses ImageMagick Engine that is installed and allows me to easily regenerate all my images.

Works as advertised

The thumbnail regeneration could be a bit faster though. I have used it for longer than I can remember, at least 5 years.

Simple, functional

Improve the quality of re-sized images by replacing standard GD library with ImageMagick.

Comment-Images vs ImageMagick Engine