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)
• https://github.com/Prinzhorn/jquery-inlog (See what your jQuery code does inside like a boss)
• https://github.com/codejoust/session.js (Get user session information)
• https://github.com/rickharrison/validate.js (Lightweight JavaScript form validation library inspired by CodeIgniter)
• https://github.com/addyosmani/jquery-ui-bootstrap (A jQuery UI theme based on Twitter Bootstrap)

Bookmarklets

• https://github.com/sparkbox/mediaQueryBookmarklet (Determine current page dimensions and current media query)

Numbers, Money & Currency

• https://github.com/josscrowcroft/accounting.js (A lightweight JavaScript library for number, money and currency formatting - fully localisable, zero dependencies)
• https://github.com/josscrowcroft/money.js (currency conversion library, for web & nodeJS

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 & Adapters

• http://sizzlejs.com
• https://github.com/ded/qwery
• https://github.com/nathansmith/adapt (serves CSS based on screen width)

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 & Mentions Plugins

• http://iplantideas.com/quicktag
• https://github.com/alexgorbatchev/jquery-textext
• https://github.com/podio/jquery-mentions-input
• https://github.com/hailwood/jQuery-Tagit (demo at http://webspirited.com/tagit, transforms an html unordered list into a unique tagging plugin)
• http://daniel-zahariev.github.com/jquery-textntags (allows you to "@tag" someone in a text message, just like you are used to on Facebook or Twitter)

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/fastrd/youRhere (demo at http://yourhere.gandtblog.com, give your readers a chance to mark their article reading- progress by just clicking it)
• 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)
• https://github.com/tristandunn/jquery-auto-geocoder (automatically geocode and display a location entered in a text field)

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