Chosen

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.

jQuery File Upload – jQuery UI version

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.

jQuery UI Draggable

Enables dragging functionality for any element.

jQuery UI Fold Effect

Folds an element first horizontally and then vertically.

jQuery UI Datepicker

Displays a calendar from an input or inline for selecting dates.

jQuery UI Position

Positions elements relative to other elements.

jQuery UI Highlight Effect

Highlights the background of an element in a defined color for a custom duration.

jQuery UI Selectable

Allows groups of elements to be selected with the mouse.

jQuery UI Accordion

Displays collapsible content panels for presenting information in a limited amount of space.

jQuery UI Spinner

Displays buttons to easily input numbers via the keyboard or mouse.