Web Essentials is an open-source extension for VisualStudio written by Mads Kristensen, a Program Manager at the Microsoft Web Platform team, which, according to its own site: 'Adds many useful features to Visual Studio for web developers'
Full details of Web Essentials can be found here and here.
The extension provides better support for HTML, JavaScript, CSS, CoffeeScript, JSHint, LESS, and TypeScript in Visual Studio 2012.
To contribute, send the pull request to Web Essentials 2012 or Web Essentials 2013 on GitHub. Also, to report the bug, open issue on corresponding GitHub repo.