This is very good app for language learning. It works very well on Samsung Galaxy 3 7.0! Go to Google Play Store. I’ve tried to download the software onto my PC and encountered some difficulties opening the application. It works fine but I don’t remember what I did to finally get it to work. Whenever I do remember what I did, I will be updating this post. Meanwhile, though, enjoy the app on any Android device and be reassured that it is absolutely free and community managed, meaning that real live foreign language (relative terms) speakers who can be contacted through brief comments on the site lessons which are responded to through email.
“…By doing a Google search, it has been covered by TechCrunch, Technology Review, New Scientist, Hacker News, etc.” –http://en.wikipedia.org/wiki/Talk:Duolingo (outdated webpost)
The Official Website– https://www.duolingo.com/
Other reviews– http://www.fluentin3months.com/duolingo/
UPDATE: I checked and the site works on PCs. I simply forgot how I registered. Have fun!