Easy responsive tabs is a lightweight jQuery plugin which optimizes normal horizontal or vertical tabs to accordion

Conveyor-Belt is a simple but well adjustable slideshow carousel jQuery plugin. There are plenty of configurations available

Hide/show password plugin says "life's too

Pronto is a jQuery plugin for faster page loads.   Building on concepts like 

Highlight Search Terms is a jQuery plugin which highlights search terms in referrer URL from Google, Yahoo, Bing

annyang is a javascript library for adding voice commands to your site, using speech recognition. This javascript speech recognition

jQuery googleslides is a simply jQuery plugin that displays your Google Photos, including Picasa and Google+ albums. There

jQuery lightGallery is a lightweight jQuery lightbox gallery for displaying image and video.   jQuery lightGallery

Text Effects is a sci-fi style awesome effect made with jQuery. As a jQuery plugin, you can simply implement the effect

jQuery responsiveText is a jQuery plugin to set font sizes responsively based on its container's width. You can use this