A few weeks ago, I was looking for a Lightbox-like script that would allow me to display more than just pictures. In addition to static images, my client required the ability to display various types of movies including QuickTime and SWF. The only script that fit the bill was Lightwindow—a nice piece of work to be sure—but it required the Prototype + Scriptaculous combo and I was already using YUI.
Besides, I thought, it would be really great to have a full-featured media viewing application that was library agnostic. Then, if I need to use a different framework for some particular reason, I can easily switch.
I've been using Lightbox JS on my site for almost 2 years. The next time I need lightbox functionality for an application, I'll definitely try out Shadowbox. I dig the look and feel. I agree with Ajaxian commentors that rel="lightbox[name]" would be awesome. If it's added, I could theoretically replace lightbox.js with shadowbox.js and I wouldn't have to make any other changes.