'Dictionary (Googleâ„¢ Translate) Anywhere' extension provides access to a floating multilingual Google Translate panel on any webpage.
Free Online Translator Toolbar help you to translate whole web page, selected text on web page or text from Clipboard using one of free online translate services. Also you can translate single words using one of free online dictionaries
Translate entire web page or selected text using google translate
There are many translators on Firefox. There are two features they're not supported:
This addon can translate all pages you can open in firefox
Translation, text-to-speech, transliteration on pages and in the pop-up for 100+ languages.
Translate selected word or phrase over translate.yandex.ru from any lang to Russian (or from Russian to English) - result in context menu (right click) and in popup. Minimum and fast. Not affect DOM. Unofficial extension - works by using API.