Fed up with the way Emacs's built in HTML-helper mode handled highlighting and other things on my last web-development project, I decided to look for a better solution. Because if there's one thing you can always be sure of, if the default Emacs is deficient in something as common as web development, SOMEBODY has written a bit of elisp to make it spectacular.
The answer, it turns out, is NXHTML mode. Although it started as a mode strictly for XHTML, this mode can do all kinds of cool stuff -- including loading multiple major modes at once.
I still haven't given NXHTML mode the full workover, but I'll test run it on my next job and see how she schoons.
If you want to try it out, head over to the website and download the zip file. Instructions are included on how to configure Emacs to use it. Hopefully the DebUntu packagers will get 'round to putting it in the repos, or else it will make the cut for inclusion Emacs24 (whenever that happens).