Coloring HTML code in template editor?

I’m looking for a plugin that colors the HTML code of the template editor. When I’m editing template files (like sidebar.php, header.php, etc.) it would be really handy to have the code colored up like most HTML editors. It’s so much easier to work with when the code and the text are visually distinct.

Does anyone know of a plugin for this? I could only find plugins that would highlight code (like PHP) that you insert into blog posts, but that’s not what I’m looking for.

Thanks!