Virtaal is a great translation tool for localization of software, but is also usable as a broader translation tool.
Virtaal is a graphical translation tool. It is meant to be easy to use and powerful at the same time. Although the initial focus is on software translation (localisation or l10n), we definitely intend it to be useful for several purposes.
Virtaal is built on the powerful API of the Translate Toolkit. “Virtaal” is an Afrikaans play on words meaning “For Language”, but also refers to translation.
A screencast tutorial is available here