Decimal.js
An arbitrary-precision Decimal type for JavaScript
Tiny Color
Fast, small color manipulation and conversion for 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**).
Mathjs
An extensive math library for JavaScript and Node.js
Babel
Babel is a compiler for writing next generation JavaScript.
Store
A better way to use localStorage and sessionStorage
Nerdamer
a symbolic math expression evaluator for javascript
Poly
Small, fast, awesome. The only ES5-ish set of polyfills (shims) you can mix-and-match because they're individual AMD modules.
Numeral
A javascript library for formatting and manipulating numbers.
Css3 Finalize
Tired of adding prefix for each broswer when it comes to the new css3 attributes?
Sprintf.js
sprintf.js is a complete open source JavaScript sprintf implementation.
Typecast.js
Typecast.js :: Solving the simple problems
Args.js
Create javascript functions with optional, default, grouped and named parameters.
Extract Values
A simple helper to extract values from a string based on a pattern.
Datejs
Datejs is an open-source JavaScript Date Library.
Bignumber.js
A JavaScript library for arbitrary-precision decimal and non-decimal arithmetic
Xregexp
Extended JavaScript regular expressions