Rene Skou

This is a simple WordPress plugin which allows a site adminstrator to convert images in the uploads folder. You simply go the the tools -> CITM page and select the images you want to convert.
Then the image will be convert to a media item and moved to a right subfolder if you have set up month and year folders.
<h4>FEATURES</h4>
*supports multi image formats jpeg,jpg,png and gif. 
*Styled and buildt just like in the core.

Convert images to media

A plugin for WordPress that convert images to wordpress media

Gennady Kovshenin

Dugonja

This plugins embeds image links in comments with the img tag so the image are visible in your comment timeline.
Image formats supported: 
1. .jpg 
2. .gif 
3. .png
You can specify your comment width so the images are fitted nicely. Images are not hosted on your server neither this plugin pickups any data.
Do note that people can link extremely large images and your page loading can be compromised because of that.
Demo: 
<a href="http://www.ascic.net/embed-comment-images/" title="Embed Images in Comments" rel="nofollow ugc">Embed Comment Images</a>

Embed Images in Comments

Plugin contains a security issue. Do not use right now.

Updated: very simple and to the point :)

Simple

Embed direct image links in your comments with an img tag.

Convert images to media vs Embed Images in Comments