I wrote about this already on another site, so I will just copy and paste.
"Readlang, despite only having a few thousand users (around three thousand, if I'm not mistaken) and being in its beta stage of production, is one of the best places on the internet to learn a language for free, in fact, it very well may be the best.
This site uses spaced-repetition and a sort of virtual immersion (via texts and, on occasion, YouTube videos) to help you learn any number of foreign languages of your choosing.
Currently, the site offers 42 languages (41 excluding English) including popular ones like Spanish, French and German, a dead language in Latin, and some fairly rare ones like Icelandic.
This is more than just a bunch of bilingual texts though, because Readlang provides you with beautifully integrated translation, a wonderfully designed algorithm to help you practice vocabulary and a reader that allows you to use these features on any webpage in your target language, not to mention the YouTube stuff or other less crucial features.
So, if, for example, I want to read a Russian news article from http://www.pravda.ru/ , then I can simply go on there, click my Chrome "Readlang" extension, and start reading. If I get stuck on a word, I click on it and it gives me a translation (along with optional alternative ones). If I get stuck on a phrase that is 8 words or less, then I just do the same (there is a limit on the phrase translation, however, unless you'd like to pay). Also, the words that you choose to translate are recorded and put into flashcards to be practiced later using the spaced-repetition model.
This site is still very young and yet very beautifully designed and one of the best language learning sites around. It is difficult to give something that is so young a five star rating, but this is already one of the best sites (along with stuff like Anki, Memrise, "X"Pod, Duolingo, LingQ, etc.) around for this and it is only getting better. "