chebum

<a href="http://visualwatermark.com/wp-photo-protect/" rel="nofollow ugc">Photo Protect</a> adds an invisible layer over your post images to protect them from copying. 
Visitors trying to save an image will get a blank image instead of your photo.
Here is why you should download it:
<ul>
<li>Protects your images. 9 out of 10 visitors won’t be able to download and copy your images.</li>
<li>Works in every modern browser. No plugins required!</li>
<li>Has no dependencies. Correctly works with every framework your theme may have jQuery, MooTools, ExtJS, GWT, etc.</li>
<li>Supports responsive themes. Applies protection in a way both theme and protection layer continue to function properly. Even if your visitor resizes her browser.</li>
<li>Works on smartphones.</li>
</ul>

Photo Protect

Adds an invisible layer over your images to protect them from copying.

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.

Photo Protect vs Comment-Images