Mapping file extensions to Emacs syntax modes
I spent much of my day at work editing Django templates in Emacs, which does a decent job of applying syntax highlighting to HTML. When I got home, though, and resumed work on a new Mango feature, my Django templates lacked colour. :\
Emacs doesn't recognize the "dhtml" extension, but it's easy to add a custom mapping (when the appropriate snippet is sitting in a chat window waiting to be copied (ty, Brodie)).
(add-to-list 'auto-mode-alist '("[.]dhtml$" . html-mode))
Adding the above snippet to my ~/.emacs file did the trick. :)

- HTML in Emacs with and without syntax highlighting