Lokesh Dhakar’s Lightbox is the original lightbox script; it is a simple, unobtrusive script used to overlay images on the current page. It’s a snap to setup and works on all modern browsers.
Using Lightbox with your images is pretty easy: simply add a rel=”lightbox” attribute to any anchor tag to activate. Additionally you can group a set of related images by including group name between square brackets in the rel attribute for each image (e.g., rel=”lightbox[group-name]“>).
Lightbox is powered by Prototype framework and Scriptaculous effects library and is licensed under the Creative Commons Attribution 2.5 License. You can find further information, demo & download on Lokesh Dhakar’s Website.