JavaScript & jQuery

Common

• https://github.com/olivernn/supplement.js (A small collection of utility functions to make working with JavaScript that much sweeter and more expressive)
• https://github.com/alexyoung/turing.js (DailyJS's JavaScript framework)
• http://sammyjs.org (tiny javascript framework built on top of jQuery, It's RESTful Evented Javascript)

Templates

• https://github.com/sstephenson/eco (Embedded CoffeeScript templates)

Loaders

• https://github.com/getify/LABjs

SlideShows

• https://github.com/nathansearles/Slides

Images

• https://github.com/odyniec/imgareaselect (select specific image area)

CSS3 Selector Engines

• http://sizzlejs.com/

Mobile

• https://github.com/joehewitt/scrollability (Imitates iOS native scrolling in JavaScript)

File Uploaders

• https://github.com/johnlanz/jquery-fileuploader
• https://github.com/valums/file-uploader
• https://github.com/filamentgroup/jQuery-Custom-File-Input

Fonts & Typography

• https://github.com/davatron5000/FitText.js

Tags Plugins

• http://iplantideas.com/quicktag
• https://github.com/alexgorbatchev/jquery-textext

DropDowns Plugins

• http://jamielottering.github.com/DropKick

Switch inputs

• https://github.com/rawnet/jquery-switch (A slide/toggle switch for jQuery)

QRCodes

• https://github.com/jeromeetienne/jquery-qrcode

Star Rating plugins

• https://github.com/wbotelhos/raty
• http://www.fyneworks.com/jquery/star-rating

Editing plugins

• https://github.com/tuupola/jquery_jeditable
• http://digitalbush.com/projects/masked-input-plugin
• https://github.com/akaihola/jquery-autogrow
• https://github.com/davatron5000/Lettering.js
• http://polarblau.github.com/suggest (simple Auto-suggest)

Search Box plugins

• http://documentcloud.github.com/visualsearch
• https://github.com/remybach/jQuery.slashSearch (This plugin allows you to give focus to the search field by typing the '/' (forward-slash) key)

Effect plugins

• http://lab.smashup.it/flip (flip easily your elements in four directions)
• https://github.com/jackrugile/jRumble (umbles, vibrates, shakes, and rotates any element you choose)
• https://github.com/hakimel/zoom.js (zoom in on any element in the DOM)

Graph plugins

• https://github.com/samizdatco/arbor