ChrisHurst

MyWebsiteAdvisor

This plugin allows you to Automatically displays a watermark on images which have been hotlinked as they are viewed on the Hotlinkers Website. 
The plugin uses PNG watermark images with transparency for precise control over the appearance of the watermarks. 
This plugin also supports simple text watermarks with adjustable color, size and transparency. 
The user friendly settings page allows for control over the appearance of your watermark. 
The watermark preview feature allows for easy testing of the plugin settings. 
The watermark size is controlled as a percentage of the target image, 50% means the watermark will be half the width of the target image. 
Watermarks are non-permenant, original images are not edited, the plugin maintains a cached copy of the watermarked image, which can be cleared and regenerated at any time!
<a href="http://MyWebsiteAdvisor.com/tools/wordpress-plugins/watermark-hotlink-protection/" rel="nofollow ugc">Upgrade to Watermark Hotlink Protection Ultra</a> for advanced 
watermark features including:
<ul>
<li>Fully Adjustable Image Watermark Position</li>
<li>Fully Adjustable Text Watermark Position</li>
<li>Adjustable JPEG Image Output Quality</li>
<li>Highest Quality Watermarks using Image Re-sampling rather than Re-sizing</li>
<li>Lifetime Priority Support and Update License</li>
</ul>
Developer Website: http://MyWebsiteAdvisor.com/
Plugin Support: http://MyWebsiteAdvisor.com/support/
Plugin Page: http://MyWebsiteAdvisor.com/tools/wordpress-plugins/watermark-hotlink-protection/
Requirements:
<ul>
<li>PHP v5.0+</li>
<li>WordPress v3.3+</li>
<li>GD extension for PHP</li>
<li>FreeType extension for PHP</li>
</ul>
To-do:

Watermark Hotlink Protection

Displays a watermark on images which have been hotlinked

sverde1

This plugin allows you to watermark your uploaded images. You can create watermark with different fonts, colors and 
apply those watermarks to different image sizes (thumbnail, medium, large, fullsize). You can also position the watermark 
anywhere on the image within Watermark RELOADED settings. Watermarking settings are simple to use and provide you with 
instant preview of how your watermark will look like on the uploaded image.
<a href="http://eappz.eu/en/products/watermark-reloaded-pro/" rel="nofollow ugc">Upgrade to Watermark RELOADED Pro</a> for more 
watermarking features:
<ul>
<li>watermark opacity</li>
<li>image watermark</li>
<li>watermark background color</li>
<li>text watermark with outline</li>
<li>text watermark with variables</li>
<li>upload time option to turn off the watermarking</li>
<li>many more amazing features</li>
</ul>
Requirements:
<ul>
<li>PHP5</li>
<li>GD extension for PHP</li>
<li>FreeType Library</li>
</ul>
To-do:
<ul>
<li>Watermark RELOADED Bug fixing (request by: all)</li>
<li>Don’t display watermark on images where watermark would overflow image (request by: alex)</li>
<li>Watermark aditional image sizes added by other plugins (request by: twincascos)</li>
<li>Watermark images that were uploaded before plugin was installed (request by: anchy-9, Blogging Junction, Ashkir, Mobile Ground, Nicolas)</li>
<li>Image size aware watermark (request by: brohism)</li>
<li>Watermark outside picture</li>
</ul>

Watermark RELOADED

Add watermark to your uploaded images and customize your watermark appearance on a user friendly settings page.

Watermark Hotlink Protection vs Watermark RELOADED