Some developer resources that I find useful.

codex.wordpress.org 
generatewp.com
wp-hasty.com

Lukes awesome WP developer tools list:
github.com/lukecav/awesome-wp-developer-tools

I will add on to the list when I came across additional resources.

When I need to know the host of a specific web site.
www.whoishostingthis.com/
hostadvice.com/tools/whois/

Boiler Plates:
designyourway.net/blog/wp/wordpress-boilerplates

smashingmagazine.com/2015/06/wordpress-custom-page-templates

One language in the backend and one in the frontend:
gist.github.com/scarstens/11378999

   // setup one language for admin and the other for theme
     // must be called before load_theme_textdomain()

     function set_my_locale($locale) {
          $locale = ( is_admin() ) ? "en_US" : "it_IT";
          setlocale(LC_ALL, $local );
          return $locale;
     }
     add_filter( 'locale', 'set_my_locale' );