We learn foreign languages while surfing the Internet

If you want to learn to speak a non-native language: surround yourself with this language. Looking for information on it, change it in all interfaces, take notes. 

The

extension will help in this well. It optionally translates words in an article or on a website into another language. For example, you read something in Russian on Wikipedia - and in the context you see a foreign word. So slowly the vocabulary will expand.  

Supports 6 languages: Spanish, French, German, Portuguese, Italian and Korean. If someone finds similar extensions for Firefox and Safari, send them to your personal account