Chosen is a javsacript plug-in that makes long, unwieldy select boxes much more user-friendly. It is currently available in both jQuery and Prototype flavors.
jVectorMap is a jQuery plugin employed to show vector maps and visualize data on HTML pages. It uses SVG in all modern browsers like Firefox 3 or 4, Safari, Chrome, Opera, IE9, while legacy support for older versions of IE from 6 to 8 is provided with VML. Using jVectorMap is pretty simple as for any other jQuery plugin
Kaiten is a jQuery plug-in which offers a new navigation model for web applications. Unlike conventional applications where the screen flush another without continuity between information and actions, with Kaiten interactions between the user and the application are a stack of contiguous screens where each screen is presented in columns.
jquery-ahm is a replacement for $.ajax. With $.ajax, every ajax request needs a callback, resulting in a lot of javascript. $.ahm reduces javascript code by letting the response data define the actual callbacks.
Reel is a jQuery plugin which takes an image tag and makes it a live "projection" of pre-built animation frames sequence. Its aim is to provide a 360° view of something or someplace. Great alternative to widely used Flash and Java techniques.