This is another install it and forget about it plugin. The easiest way to descrive what Auto Thickbox does is to ask you to click on an image within a post. So click the thumbnail below, and you’ll see the plug-in in action…
Fabulous Furry Freak Brothers - The Movie - Snapshot
With a normal WordPress install, when you click on an image, one of two things will happen. Either the browser will display just the picture, or if the blogger has elected to use image posts, the browser will display the image in what looks like a new post, just for the picture. Now, whether you are displaying a photo, or a much delayed film of an outstanding comic series, the visitor will see the picture in an overlay, with the rest of the site greyed out in the background. If you have multiple pictures within one post, the plug-in will turn the experience into a basic gallery, and the visitor can navigate through the images without having to return to the original post each time.