A new Mac includes support files and documentation written in dozens of languages besides English. If you are fluent in only one or two languages, I recommend using a free program called Monolingual to delete unneeded localization files that take up hundreds of megabytes of disk space on a typical system.
To use Monolingual, you need to be logged in as an administrative user or as root. When Monolingual starts, you will be asked to choose the languages you wish to remove from your system. Once you make your selection, press the Remove button. To confirm your decision, enter your administrator password. Once you remove the localization files, the only way to restore them is to reinstall Mac OS X.
Monolingual requires Mac OS X 10.3.9 and higher and is distributed under the GNU General Public License as published by the Free Software Foundation. I recently installed a fresh copy of Mac OS X 10.5 (Leopard) on my laptop and recovered 849 MB from my drive after running Monolingual.
The most recent version of Monolingual is available at http://monolingual.sourceforge.net/. If you like Monolingual and want to support its development, you can donate a small amount via SourceForge’s donation page.