Chosen is a JavaScript plugin that makes long, unwieldy select boxes much more user-friendly. It is currently available in both jQuery and Prototype flavors.
File Upload widget with multiple file selection, drag&drop support, progress bars and preview images for jQuery. Supports cross-domain, chunked and resumable file uploads and client-side image resizing. Works with any server-side platform (PHP, Python, Ruby on Rails, Java, Node.js, Go etc.) that supports standard HTML form file uploads.
Displays collapsible content panels for presenting information in a limited amount of space.
Displays buttons to easily input numbers via the keyboard or mouse.
Pulsates an element n times by changing the opacity to zero and back.
Displays a flexible slider with ranges and accessibility via keyboard.
Lists suggested words as the user is typing.
Provides a factory for creating stateful widgets with a common API.
Duplicates and extends the functionality of a native HTML select element, allowing it to be customizable in behavior and appearance far beyond the limitations of a native select.
Fades an element.