Mac OS X's rigid folder structure doesn't allow you rename folders like Applications, Library, Users, System, etc. However, you can take advantage of Mac OS X 10.2's file system localization feature to change how these folders are displayed -- even in English.
Using your text editor of choice, edit this strings file: System -> Library -> CoreServices -> SystemFolderLocalizations -> en.lproj -> SystemFolderLocalizations.strings. If you use Mac OS X in a language other than English, edit the file in the directory for your language.
Suppose you want to rename Library to Stuff. You'll want to change this line:
"Library" = "Library";to read
"Library" = "Stuff";At the top level, you may rename System, Applications, Library, Users, Shared, and Utilities. In your home directory, you can rename Desktop, Documents, Movies, Music, Pictures, Public, Sites, and Drop Box. Log out and log back in and you should see the directories renamed. This change does not actually rename anything in the file structure, so if you browse your files in the Terminal you won't see any changes (and software which expects certain names will continue to work).
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020926061746306