Single most useful example of using dired (Emacs)

Question

What is your single most useful example of using dired mode in Emacs? Any nice tricks? Please one example per answer.

Answer 1

For me wdired is one of the nicest feature to be used with dired, it allows to do all sorts of emacs editing magic things on a directory to be able to rename the files, see some of the documentation on the emacswiki's page :

http://www.emacswiki.org/emacs/WDired