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.

malcalevak

A WordPress implementation of the stellar Slimbox2 script by Christophe Beyls (an enhanced clone of the Lightbox script) which utilizes the jQuery library to create an impressive image overlay with slide-out effects.
Almost, if not all, options are configurable from the administration panel. For more on the settings and what they do check out the <a href="http://www.digitalia.be/software/slimbox2/" title="Slimbox 2, the ultimate lightweight Lightbox clone for jQuery" rel="nofollow ugc">Slimbox2</a> page.
Support forums are generously hosted by Ryan Hellyer of PixoPoint, <a href="http://pixopoint.com/forum/index.php?board=6.0" rel="nofollow ugc">here</a>.
Recent Changes in v1.1.3.1: 
1. Changed index.php to UTF-8 without BOM encoding to resolve issues for some users. 
Recent Changes in v1.1.3: 
1. Updated to Slimbox 2.05 to support WordPress 3.6 
2. Removed unnecessary xfarbtastic.css
<h3>Credits</h3>
Thanks to the following for help with the development of this plugin:
<ul>
<li><a href="http://www.digitalia.be/software/slimbox2" rel="nofollow ugc">Christophe Beyls</a> – Creator of the Slimbox2 Javascript</li>
<li><a href="http://gsgd.co.uk/sandbox/jquery/easing/" rel="nofollow ugc">George McGinley Smith</a> – Creator of the jQuery Easing Plugin Javascript</li>
<li><a href="http://acko.net/dev/farbtastic/" rel="nofollow ugc">Steven Wittens</a> – Creator of the jQuery Farbtastic colorpicker Javascript</li>
<li><a href="http://pixopoint.com" rel="nofollow ugc">Ryan Hellyer</a> – For spurring my interest in WordPress plugins by welcoming my assistance on his <a href="http://pixopoint.com/multi-level-navigation/" rel="nofollow ugc">Multi-level Navigation plugin</a> and for hosting our <a href="http://pixopoint.com/forum/index.php?board=6.0" rel="nofollow ugc">support forums</a>.</li>
<li>Spi for code suggestion to autogroup items by post.</li>
<li><a href="http://nv1962.net/" rel="nofollow ugc">nv1962</a> – Suggestion to implement localization and Spanish/Español and Dutch/Nederlandse translations.</li>
<li>Laws for German/Deutsch localization.</li>
<li>monodistortion for CSS tweaks to prevent tiling of images.</li>
<li>Jandry for the French/Français translation.</li>
<li><a href="http://www.serhatyolacan.com" rel="nofollow ugc">Serhat Yolaçan</a> for the Turkish/Türkçe translation.</li>
<li><a href="http://pc.de" rel="nofollow ugc">Marcis G.</a> for the Belarusian/Беларускі translation.</li>
<li><a href="http://www.easespot.com" rel="nofollow ugc">easespot</a> for the Chinese/中文 translation and FunDo for additional assistance.</li>
<li><a href="http://www.techload.com.br/" rel="nofollow ugc">Marcelo</a> for the Brazilian Portuguese/Português brasileiro translation.</li>
<li><a href="http://www.Behumandesign.com" rel="nofollow ugc">Giacomo</a> for the Italian/Italiano translation.</li>
<li>Nata Strazda of <a href="http://www.webhostinghub.com" rel="nofollow ugc">Web Hub</a> for the Lithuanian/Lietuviškai translation.</li>
<li>ackie00h for the Japanese/日本語 translation.</li>
<li>nafanyabr for the Russian/русский язык translation.</li>
<li><a href="http://shachi.tw" rel="nofollow ugc">shachi</a> for the Traditional Chinese/繁體中文 translation.</li>
<li>Zareiff, for various Next/Previous/Close translation images when not provided by translators.</li>
<li>Anyone else I forgot to mention who’s made a suggestion or provided me with ideas.</li>
</ul>

WP-Slimbox2 Plugin

A WordPress implementation of the Slimbox2 javascript.

Photo Protect vs WP-Slimbox2 Plugin