Roar is a notification widget that streamlines incoming messages, such as updates or errors, without distracting the user from their browser experience or breaking their work-flow by displaying obtrusive alerts.

Facebox is a jQuery-based, Facebook-style lightbox which can display images, divs, or entire remote pages.

ModalBox is a JavaScript technique for creating modern (Web 2.0-style) modal dialogs or even wizards (sequences of dialogs) without using conventional popups and page reloads. It’s inspired by Mac OS X modal dialogs. And yes, it may also be useful for showing bigger versions of images.

Shadowbox is an online media viewer application that supports all of the web’s most popular media publishing formats. Shadowbox is written entirely in JavaScript and CSS and is highly customizable. Using Shadowbox, website authors can showcase a wide assortment of media in all major browsers without navigating users away from the linking page.