Drupal: Multilanguage

Content Translation
http://drupal.org/handbook/modules/translation

Local: Multilanguage Support
http://drupal.org/handbook/modules/locale

Translation for Download
http://drupal.org/project/Translations

Localization Server
http://drupal.org/project/l10n_server

Internationalization
http://drupal.org/project/i18n

Menu Translation
http://drupal.org/project/menutranslation

Active Translation Module
http://ftp.drupal.org/files/projects/active_translation-6.x-1.3.tar.gz

Consistent Language Interface
http://drupal.org/project/languageinterface

Module:
http://ftp.drupal.org/files/projects/languageinterface-6.x-2.1.tar.gz

This module provides a language switching block that is very similar to that provided by the core locale module, however its behavior differs from the locale block in several ways:

1. The visibility of language links in the block is consistent and independent from the existence of translations for the page that you are viewing. The logic here is that the user should be able to change the language of the interface at all times. This is important because often there are menus and blocks that are language specific and the user should always be able to find the link back to their language.

*** For those who would like to have it so that languages which are not translated also do not have language links you should use the Language Icons module in conjunction with the core Locale module. ***

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