DefProc

WordPress plugin to automatically add rel=”lightbox” attribute to link wrapped images, as placed into WordPress posts.
This plugin requires lightbox or slimbox (or any lightbox-compatible image handler) to also be installed on your site, either as part of the theme, or via a plugin. If either lightbox, or add-rel-lightbox is not activated at any time, your site will revert gracefully to the standard “open image as new page”.
The plugin currently only works with images placed into posts using the “add media” dialogues, and will only apply to images that are in your media library. However, it will also not interfere with any images that have already have attributes applied to them.
add-rel-lightbox also works with the [gallery] shortcode, adding the rel=”lightbox” attribute to links created by it. Note that you will have to use the <code>[gallery link="file"]</code> format, or select “Image File” when inserting the gallery for lighbox to work as expected. Galleries that link to the attachment page are unaffected by this plugin.
In addition to applying rel=”lightbox”, this plugin will retrieve the media library caption for any images, and correctly escape any html entities, so that the caption is displayed as expected in the lightbox.

add-rel-lightbox

Add rel="lightbox" to <a> wrapped image links in the content and to [gallery] image links, and include captions for lightbox/slimbox

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.

add-rel-lightbox vs WP-Slimbox2 Plugin