Apertium is Free software for machine translation (MT). It started as a project to translate between closely related languages, but later versions also supported language pairs that were not that close to each other. Most of the current language pairs offered by Apertium do not use English as the source language.
Virtaal has a plugin to provide the Apertium output as suggestions. Contact the Apertium project for information on what language pairs are supported, what quality can be expected, and to hear how to get involved. More information is available on their wiki.
The plugin queries a web service over the Internet, and suggestions might therefore take a moment before they are displayed. Future versions might be able to make use of a locally installed copy of Apertium. Join us to make this a reality. Also keep in mind that your source text is sent unencrypted over the Internet, and therefore no confidential translation should be done using this plug-in.
Remember that the suggestions from the Apertium plugin are unreviewed machine-generated translations, that could be wrong, inaccurate, or flawed in some other way. It is meant as a way to help you increase your productivity, not to substitute the expertise of a human translator.