Another Lightbox like library with JQuery UI

TopUp is another easy to use Javascript library for unobtrusively displaying images and webpages in popups. The library is jQuery and jQuery UI driven in order to maintain cross-browser compatibility and compactness.

TopUp is absolutely free, also for commercial use. The installation of TopUp consists of including only one file (no images or stylesheets), the look-and-feel is Apple-like, the animations and transitions look fancy, you can still use Prototype, it is so easy to specify options and last but not least: you can stay updated with the latest version without changing any code.