Learn languages for free online
English, Spanish, French, German, Italian, Japanese, Portuguese, Russian, Polish, Turkish, Arabic, Chinese
Limitations: Content is limited in the free version.
Web app (and browser extension for Chrome) that lets you double-click any word to get a translation. It adds the words you click to a vocabulary list and quizzes you on them when you're ready. A wide variety of language available.
Great online dictionary for German to English, but also German to other languages include Spanish, Finnish, Italian, French, and over 20 other languages.