Duolingo

Created by a Carnegie Mellon professor Luis von Ahn, Duolingo is free language learning site that currently offer lesson in learning Spanish, English, Italian, Portuguese and German. 

Like many others, Duolingo use gamification to spice up the learning process with score and leaderboard. The usual session is in the form of Duolingo gives you some explanation about the current topics and then give you related questions. The interesting thing is in every session you have limited "lives" in the form of heart. Every time you answer incorrectly you lose one heart and if you give wrong answer when you no longer have any heart, its all over and you have to start over from beginning. Just like when playing games it can give you a sense of dread like "Oh my God, there is still six questions left and I already lost all my hearts". I never thought that learning language can be so intense.

The original idea of Duolingo is actually to make a crowdsource translation site and that goal is implemented in the feature that let Duolingo take random quote from the internet and ask you to translate it. It's really neat idea to familiar you with the real world usage of the language that you are currently learning. Your translation will be compared with other people translations so you can see how accurate your translation is.

This day, the success of a website is usually means making a vibrant community built around it. Duoling has discussion feature where Duolingo users can engage with each other. Discussion is really like forum when one user post a question and others answer it but it placed right inside the main site.

All in all, it's a pretty good site. Highly recommended.