Shadowbox is an online media vieiwing application similar to Lightbox and Thickbox but with more functionality. Supports all types of media.
Automatically enables thickbox on thumbnail images (i.e. opens the images in a fancy pop-up).
This plugin for WordPress automatically add the rel="lightbox[ID-OF-THE-POST]" and recovers the image title.
Always Valid Lightbox is a Lightbox plugin whose markup adapts to the WP site's Doctype, in order to always provide valid HTML markup.