everygain Translator's main advantage, in comparison to other online translation tools (like the Google Toolbar), is that you don't have to translate the whole page and can select the part of the text you want to get translated.
Twitter, facebook and the most forums are also supported with a one-click-translation, so that you don't need to select the text that you want to translate.
You can also use a shortcut to get the translation of the selected text or an input field to translate your own text. Just use ALT+T and the translator comes up.
For the translations the everygain Translation is using google's translation API.
· Mozilla Firefox