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.

ModalBox is built with pure JavaScript and is based on Sam Stephenson’s excellent Prototype JavaScript Framework, script.aculo.us and valid XHTML/CSS. ModalBox uses AJAX to load content.

Features of Modal Box

• Web 2.0-ready. ModalBox uses industry-standard libraries — prototype and script.aculo.us.
• AJAX pages loading. ModalBox uses AJAX instead of deprecated iframe for content loading. It’s also more secure — you can’t access pages which are not on your host.
• Callbacks support. You can attach your own JavaScript events after showing or hiding (and more) the ModalBox
• Browser and platform independent. Since most of modern browsers use popup blockers, it’s hard to find another way to create 100% browser-compatible modal dialogs.
• Multi-purpose. You can create complex wizards to guide users through the process. Image slideshows can be done too.
• Keystrokes support. Use ESC key to close ModalBox.
• Customizable Look & Feel. Use CSS to make ModalBox look like you want.
• Supports transitional effects. Slide down appearing and on-the-fly resizing.
• Lightweight. Just about 10 KB of code.
• Works in most modern browsers. Tested in IE6, IE7, Firefox 1.0, 1.5, 2.0, Safari, Camino, Opera 8 and 9.

You can find more information, download link and demo of Modal Box here.