ColorBox – Free jQuery Lightbox plugin

ColorBox is a jQuery Lightbox plugin which is lightweight (9kb) & supports photos, photo groups, slideshow, ajax, inline, and iframed content.

The lightbox has a very nicely designed interface which can be improved or customized with CSS.
ColorBox is unobtrusive, every option is mentioned in the JS & requires no changes to the existing HTML.

For faster displays & slideshows, it preloads background images and, optionally, can preload upcoming images in a photo group.

The plugin comes with a bunch of settings, including transition types-speeds & opacity, for maximum customization.

Demo:http://colorpowered.com/colorbox/core/example1/index.html
More Info&Download:http://colorpowered.com/colorbox/