jQuery UI provides abstractions for low-level interaction and animation, advanced effects and high-level, themeable widgets, built on top of the jQuery JavaScript Library, that you can use to build highly interactive web applications.
ThickBox is a webpage UI dialog widget written in JavaScript on top of the jQuery library. Its function is to show a single image, multiple images, inline content, iframed content, or content served through AJAX in a hybrid modal.
The Aptana IDE is a free, open-source, cross-platform, JavaScript-focused development environment for building Ajax applications. It features code assist on JavaScript, HTML, CSS, FTP/SFTP support and a JavaScript debugger.
yourminis.com is a personalized dashboard of minis (mini applications, also known as widgets) that let you perform specific tasks, and get information and features from all over the web in one place.