What are popular or maybe not so popular (but also useful) web applications, which center around the theme of language learning?
BBC has a comprehensive language learning site. 36 different languages!
Check out LiveMocha
Livemocha is the world's largest online language learning community! 6 million Livemocha members appreciate our simple, effective approach to language learning: the most natural way to learn a language is with help from real native speakers.from real native speakers.
Check out smart.fm
It is not strictly for language learning as it covers all different subjects but it has pretty good resources on languages.
The content is partially created by smart.fm itself but the large part of it is created by the user community. I went through SAT Verbal programme to work on my English vocabulary and I found it pretty good. My favourite feature of the app is the fact it organises the repetitions for you.
They also have an iPhone app which is a bit limited at the moment but allows you to do some learning on the go and can be used off-line.
Babbel is a good one which just recently supports voice recognition. The voice recognition wasn't that great when I tried it out, but it looks good nonetheless. Only for a few European languages though.
EduFire - http://edufire.com/ - is good. It is also not exclusive for languages, but it has some tools for that purpose, such as the flashcards for vocabulary.
I thought this guy has an amazing little video about the different options out there: http://www.youtube.com/watch?v=tYO5aw4wPHE&feature=fvw
Try http://www.babelreader.com It allows you to directly read foreign language blogs and websites. It keeps track of the words you know and the words you are learning. You can export words and marked phrases to Anki for review. It is better to read about something you are into than dry school textbooks. The drawback is that you need to find the blogs you are interested in by yourself. Non an easy task in the language you don't know yet.