Elio Rivero

ILC Thickbox will parse your post content looking for images with the class ilctb. When found, it will display the image within a thumbnail and when clicked it will launch the original size image using Thickbox.
The modal dialog and the thumbnail wrapper is currently handled by ThickBox, which requires jQuery. Both Thickbox and jQuery are safely loaded from the versions included with WordPress using wp_enqueue_script.
This software is provided without warranty of any kind.

ILC Thickbox

Display an image as a thumbnail and launches Thickbox for a larger view.

David Riccitelli

Modal is a WordPress plugin that enables you to create modal dialogs from posts or pages.
Features include:
<ul>
<li>Create a modal dialog from any page or post.</li>
<li>Define the size of the dialog.</li>
</ul>

Modal

Enable modal pages and posts on your blog. Create modal forms for better calls to action!

ILC Thickbox vs Modal