Bork Bork Bork! - Ever wondered how a webpage would like if it was written like The Swedish Chef from The Muppet Show wrote it? This extension will show you.
Chinesepera-kun: Chinese Popup Dictionary - Highlight simplified or traditional characters and get an on-screen translation of Chinese in to English.
Chinup - Chinese Popup Translator - Hover a Chinese word and get a translation in a small popup window.
East Asian Translator - Translate webpages or text from Chinese, English, Japanese and Korean, using the services from excite.co.jp.
EHTip - Lets you translate English and Croatian back-and-forth.
FoxLingo - Translates web pages, lets you search in other languages, auto-translates and much more.
Free Translate! - Works back-and-forth between English and Russian, German, and French.
gTranslate - Quickly translate a snippet of text into another language using Google's translator.
ImTranslator - Enter a snippet of multilingual text and check it for correctness. Also features translation editor, virtual keyboard, spell-checker, dictionary, decoder, back translation and an email client.
InTranslate - Translate words to-and-from Greek, and look them up in Wikipedia.
Moji - A sidebar dictionary for Japanese and Chinese, including Kanji.
PeraPera-kun - Highlight Japanese kanji on a page, get an on-screen translation. Needs a downloaded dictionary.
Qwara Toolbar - Allows translation of multiple languages an can be set to do so autmoatially.
Russ Key - Type in phonetic Russian and transform to Cyrillic, and includes English translations.
Simple Translate - Lets you translate text to-and-from English/German.
SpanishTrans - Highlight a word and translate it to Spanish, including complicated terms such as conjugated verbs.
To/From Amharic - Select a word, right click, and you can chose â€œTo Amharicâ€ or â€œTo Englishâ€.
Traduku - Translate text or web pages to Esperanto.
Translation Panel - Adds the ability to translate several languages in to English.
Translator - Translate pages with the click of a button using one of the numerous online translation services.on a regular basis to aid in your grocery shopping.
lernu-fr - With each page load you get a Esperanto-French word translated in the status bar.
Morse - While the military may no longer use it, it never hurts to learn morse code as you go about your day.
WordLearner toolbar - Load any dictionary and learn new vocabulary as you surf.
Foreign Character Entry
abcTajpu - Either using macros or context menus, will let you enter accented letters, international characters or symbols.
Any Key - Allows you to type phonetic Amharic, Arabic, Armenian, Greek, Hebrew, Hindi Davangari, Mongolian, Russian, Ukrainian.
Indic IME - Assists in entering Indian text in web forms.
Leet Key - While not exactly a foreign language, turns typed text to L337, ROT13, BASE64, HEX, URL, BIN, DES, AES, Morse code, DVORAK keyboard layout and more.
Locale Switcher - Lets you change the locale of your Firefox on the fly to access different language packs.
Quick Locale Switcher - Has over 200 locales, switches spell check to the chosen locale and more.
Russian hot keys bugfix - Helps with Russian and Ukrainian key entry in Mozilla products.
Zombie Keys - Add shortcuts for international characters. (via)