Language stuff:

Important Packages are these (replace de with your langauge's ISO code):

Basic language support: language-pack-de

More language support: language-support-de

To find more application's language use:
  aptitude search -- -de$

I recommend always to install the english, too, i.e. language-pack-en

For example:
  sudo apt-get install language-pack-en language-pack-de language-support-de

The have all locales (re)generated, do
  sudo dpkg-reconfigure locales

To make your language the default, edit /etc/environment and /etc/default/locale to set LANG to whatever seems appropriate from/var/lib/locales/supported.d/*, e.g.:
export LANG="de_AT.UTF-8"

Timezone stuff:

Just call
  dpkg-reconfigure tzdata

But don't trust Java JREs to get that right, rather tell your application somethink like this:
  TimeZone.setDefault(TimeZone.getTimeZone(configProperties.get("timezone", "Europe/Vienna")));


From: IBCL BLog.
Originally posted: 2008-04-07