Onsen : Open source HTML5 hybrid app framework for PhoneGap & Cordova
Mobile-optimized HTML5, CSS and JavaScript with Web components
Responsive layout, Materi...
320 and up : ‘320 and Up’ is a lightweight, easy to use and content first responsive web design boilerplate.
Email-Blueprints : Email Blueprints is a collection of HTML email templates that can serve as a solid foundation and starting point for the design of emails.
This Is Responsive : Tips, Resources and Patterns for Responsive Web Design
enquire.js : A lightweight, pure JavaScript library for responding to CSS media queries.
HTML5 Boilerplate helps you build fast, robust, and adaptable web apps or sites. Kick-start your project with the combined knowledge and effort of 100s of developers, all in one little package.