Crow Translate utilizes Google, Yandex, and Bing translate API for a lightweight translator with many features.
Crow Translate runs in the system tray providing quick access to the translation task-oriented interface. You choose the languages you need to work with, and it provides the translation from one of the three engines offered. You can set it to speak the translation, which will work with the source and the translation. If you have used Google translate then, it will be very familiar. Crow Translate is capable of translating from the screen or via a user-defined selection. It supports 125 languages - even Klingon. If you prefer, it also supports a command-line interface with rich options.
One nice option is it permits compiling a group of often used languages that allows for quick changes between them without searching through a list each time, as is the case with Google translate, for instance. A nice little Open Source translator provides a number more settings options than similar apps, and you can download it as portable so you can have it with you when needed.