List of resources for Windows 8 Metro on writing apps using HTML/CSS/JavaScript?

For samples, you can start with http://code.msdn.microsoft.com/windowsapps/.

Note that you can narrow down your search criteria by selecting the desired language (this is present on the left pane).

For high level concepts and tutorials: http://msdn.microsoft.com/en-us/library/windows/apps

Javascript language reference: http://msdn.microsoft.com/en-us/library/windows/apps/d1et7k7c.aspx

Windows programming (UI) with Javascript: http://msdn.microsoft.com/en-us/library/windows/apps/br211669.aspx

Using WinJS controls (appbars etc.) http://msdn.microsoft.com/en-us/library/windows/apps/hh465493.aspx

HTML & CSS http://msdn.microsoft.com/en-us/library/windows/apps/br229576.aspx

Note that not all samples work correctly. They have several runtime issues, the most common one being that a call to "WinJS.ProcessAll" is missing (this is required for most of the winJS controls). Second one is that references to required JS files are missing. I will recommend starting with the 'quick start' link: http://msdn.microsoft.com/en-us/library/windows/apps/hh465493.aspx