When the Debian installer starts, it will normally ask you what language you want to install in and gives you a really long list of languages to choose from. Unfortunately, that's not how it works when you install on a headless NAS device. The reason for this is that installations on NAS devices are done via SSH and the installer normally brings the network up after asking the user for their language. So we'd simply skip the language question and go with English.
When Timo Jyrinki recently mentioned that he couldn't install in Finnish, Frans Pop pointed out that localechooser has changed a lot since etch and that it should now be possible to have the language question after setting up the network. This turned out to be correct and I managed to choose a different language but the installer still showed everything in English. Frans reminded me that the installer drops all translations that are not necessary but unfortunately this happens too early in our case. He pointed me to a variable that determines whether translations will be dropped. So in lenny translations will not be dropped on NAS devices that have enough RAM and users will be asked when they connect to the installer via SSH what language they'd like to install in.