You probably use M-! to run a quick shell command now and then, when you don't want to be bothered with a full M-x shell. But if, like me, you're a former XEmacs user, then you probably find FSF Emacs' default lack of tab-completion for files in the minibuffer rather annoying. Well, your pain ends here:
(if (not (string-match "XEmacs" emacs-version)) (progn (defadvice read-from-minibuffer (around tab-is-pcomplete-in-minibuffer activate) "Bind TAB to pcomplete in minibuffer reads." (let ((keymap minibuffer-local-map)) (define-key keymap "\t" 'pcomplete) (ad-set-arg 2 keymap) ad-do-it))))
Ta-da. Now when you M-! mv LongAnnoyingFileName.java LongAnnoyingFileNameFactory.java, you'll be able to tab-complete the filename.
Incidentally, who knew that elisp supported aspect-oriented programming? Apparently it does. Astonishing. I owe this tip to a co-worker, who I'd name except that I doubt he'd want to be associated with the other content on this blog. (p.s. AF, if you ever run across this post and don't mind being credited, I'll happily add your name.)