Augment.js
Modern JavaScript in your IE
Char Funk
a Unicode character utility for JavaScript
Date
Date() for humans
Nerdamer
a symbolic math expression evaluator for javascript
Moment
Parse, validate, manipulate, and display dates in javascript.
Classing Js
Brings the world of classical OOP to javascript
Auto Numeric
autoNumeric is a jQuery plugin that automatically formats currency (money) and numbers as you type on form inputs. It supports most International numeric formats and currency signs including those used in Europe, North and South America, Asia and India (lakhs**).
Datejs
Datejs is an open-source JavaScript Date Library.
Typecast.js
Typecast.js :: Solving the simple problems
Timezone Js
Timezone-enabled JavaScript Date object. Uses Olson zoneinfo files for timezone data.
Mathjs
An extensive math library for JavaScript and Node.js
Svgeezy
Allows for automatic Image fallbacks for browsers that can't handle SVGs
Numeral
A javascript library for formatting and manipulating numbers.
Ratio.js
Rational numbers for Javascript
Taggd
A tool to show and add tags to images
Store
A better way to use localStorage and sessionStorage
Css3 Finalize
Tired of adding prefix for each broswer when it comes to the new css3 attributes?