Travel site available in English, Japanese, Korean, Chinese, and Indonesian. What makes this interesting for Japanese learners is the option to choose an "Easy Japanese" version.
I have found that this site is much better for language augmentation than actual language acquisition. The exercises and topics are useful for adding to what an individual already knows and are useful for brushing up skills.
The ability to test into a level is an added bonus!
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.
A pedagogical reference grammar that combines explanations with surreal dialogues and cartoon images. Originally built for students at the University of Texas at Austin as a user-friendly guide to French grammar, this web site may be profitably used by any learner of French, provided he or she possess a sense of humor.
Français interactif is a unique, award-winning 1st-year French curriculum used by learners all over the world. Students explore French language and culture by following the lives of real students who have participated in the UT Summer Program in Lyon, France. The online curriculum includes over 320 videos, vocabulary and phonetics audio, online grammar reference with self-correcting exercises and audio dialogues, verb conjugation and practice tools, internet activities, and a textbook of classroom exercises. Français interactif was awarded the 2009 CALICO Esperanto Access to Language Education Award and the National Endowment for the Humanities EDSITEment Best of Humanities on the Web award (2005)