FaceBox, is yet another way of implementing this functionality, but styled in a similar manner to FaceBook’s pop-up boxes.

FaceBox can display DIVs, images, AJAX-loaded pages, or you can just write content in dynamically via JavaScript. It’s fairly easy to implement the script, though it took me a little bit of tweaking to get all of the images to display correctly (I just had to change a few paths throughout the code).

The JavaScript file is just 6KB, and the 1KB worth of CSS can easily be pasted into your existing stylesheet, or referenced separately. There are also a few assorted images that are required, though they’re mainly under 1K. Also note that FaceBox requires jQuery to function, so you may not want it if you’re a Prototype aficionado.