Auto Thickbox

It uses the WordPress' built-in Thickbox library to show thumb images in their full aspect ratio.

Installation:

Unpack and upload it to the /wp-content/plugins/ directory.
Activate the plugin through the 'Plugins' menu in WordPress.

What is new in this release:

• Tweak to handle image paired with link classes better.

What is new in version 3.1.1:

• Handle nested parenthesis in JavaScript event attributes on links and images.

What is new in version 3.0.2:

• Fixed broken translations.

What is new in version 2.4.1:

• WP 3.8 compatibility.

What is new in version 2.3:

• New link attribute parsing code to handle various image link configurations.

What is new in version 2.2:

• WP 3.6 compat
• PHP 5.4 compat

What is new in version 2.1:

• Supports AJAX content. Internal files are displayed on the page without iframe.
• Supports inline content (#TB_inline) on the page.

What is new in version 2.0.1:

• Restore the nothickbox functionality.
• German and Brazilian Translation (requires WP 2.9 for the js part).
• Force a higher pcre.backtrack_limit and pcre.recursion_limit to avoid blank screens on large posts.

Requirements:

• WordPress 3.1 or higher