Because sometimes cool things happen when people and technology interact.
I saw this video and thought it was some sort of company trying to scam me (or something). But it turns out Duolingo is totally legit and very interesting.
Duolingo from Trunk Animation on Vimeo.
Here's the link to the actual site, Duolingo (it's also beneath the video).
Then, while trying to learn more about Duulingo, I came across this TEDx talk by Luis von Ahm, the man who brought the world CAPTCHA and reCAPTCHA. In the (somewhat amusing) video, he describes some things about CAPTCHA and reCAPTCHA (that part was really interesting. I had no idea what it was or what it was accomplishing). Then he goes on to explain Duolingo.
It's long, but it's worth watching.