AndersZ/Lumebox
The Lumebox is an Open-Source (GPL) Lightbox clone written as a JavaScript jQuery plugin (weighing in at around 11kB minified) with a few added features. One of the main features is that it adapts according to device type with mobile optimizations, another is that it can parse RSS feeds just as easily as displaying images. The plugin searches the post or page for links leading to images (and RSS-feeds) and opens them in a popup instead of following them.