Hover-Over-Popups, CSS/XHTML-friendly, see also http://www.nicolashoening.de/?twocents&nr=8
Popline is an HTML5 Rich-Text-Editor Toolbar
jBox is a jQuery plugin that makes it easy to create customizable tooltips, modal windows, image ...
Reactjs component for spawning custom popups at mouse position.
hint.css by jQuery
A modal dialog box plugin for jQuery
Light and responsive lightbox script with focus on performance.
A prototype/lowpro based Facebook-style windowing solution
Avgrund is jQuery plugin with new modal concept for popups
bPopup is a lightweight jQuery modal popup plugin (only 1.34KB gzipped). It doesn't create or sty...
Generate CSS tooltip arrows
Tooltip popup for jQuery
Fast & light modal popup creator providing rich configuration and styling
An alternative to original alert, confirm and prompt.
A jQuery tooltip plugin