Selectivizr adds support for 19 CSS3 pseudo-classes, 2 pseudo-elements and every attribute selector to older versions of IE.
A fast & lightweight polyfill for min/max-width CSS3 Media Queries (for IE 6-8, and more).
Respond.js enable responsive web designs in browsers that don’t support CSS3 Media Queries (IE 8 and earlier versions of Internet Explorer).
Response is a jQuery plugin that helps optimize cross-device performance by enabling progressive enhancement of content via HTML5 data.
Response JS is a jQuery/Ender/Zepto plugin that gives web designers tools for building performance-optimized, mobile-first responsive websites. It provides semantic ways to dynamically swap code blocks based on breakpoints and serve images (or other media) progressively via HTML5 data attributes.
5. CSS Pie
You can write CSS3 without worrying about IE6 – IE9 fallback; Pie makes Internet Explorer to supported many CSS3 properties like Border-radius, RGBA, Gradient, Box-shadow etc…