Title: YUI PhotoViewer

There are tons of lightbox apps out there, but none that I could find that use YUI. I'm sure there are lots of developers out there already using YUI and don't want to have to use another library such as jQuery to get lightbox functionality. I have two demos available from the link below and you can download a zip file of the complete application including the YUI files needed.

Supports 3 modes (LightBox, Overlay and Remote), but many many more configurations

Project URL: http://nicora.net/projects/lightBox/