Vanilla JavaScript Plugin

Popbox.js  

A tiny plugin for creating customized, stackable modal windows and notifications.

Plugin Website  Demo

Related plugins

Snazzy Info Window  

A helper for creating highly customizable and dynamic Google Maps marker info popus.

dndod popup  

Simple and easy library for creating modal window messages, alerts, and confirm dialogues.

Vanilla Modal  

A flexible, CSS-powered modal window for images, videos and HTML. Lots of options and actively developed.