Okay, I knew about the Python shortcut—I mentioned it in Going Offline—but I had no idea it was so easy to do the same thing for PHP. This is a bit of a revelation for me!
Once in the desired directory, run:
php -S localhost:2222
Now you can go to “localhost:2222” in your browser, and if you have an index.html or .php file in your root directory, you’re in business.