If you are looking for a light box then I would suggest shadow box, the site is shadowbox-js.com
There is a MooTools version of shadow box.
I second cera box! I have been using it a lot. It is really very flexible, and support is good. http://cerabox.net/a few examples of it in use;http://www.livingstonehfx.ca/gallery (top 3 images open slide shows as iFrame, bottom thumbnails)http://www.snairbrothershotrods.ca/completedProjects.php (all the thumbnails)http://www.paintingthepack.ca/index.php#jump-portraits (all the pet pictures, and gallery link, all as one gallery)http://www.idoweddingsaway.ca/realWeddings.php (the "read our story" link on most slides)I also tried MilkBox, (http://reghellin.com/milkbox/) but choose CeraBox over it