Katakana Study is a pack with over 300 exercises that allows you to learn Katakana. For example, at the beginning, when you don’t know any katakana characters and you’re learning the ア character (which reads ‘a’ in romaji), whole Japanese words in the exercises are written in romaji with only the ア character written in katakana: アrumi (arumi), アrabu (arabu), アideア (aidea), etc.
InstantTranslate makes it really easy to translate a selection of text in the application you are working in from one language to another language.
One World Dictionary by Ascendo is a leading multilingual reference tool for Apple desktops.
