Social media to learn a new language

In addition to Duolingo, there are other social media to learn a new language. For example,

BusuuItalki
Lang-8
Live Mocha
My Happy Planet
Palabea
VoxSwap

All of them provide learners opportunity to find native speakers of the new language to help correct writing, chat, watch instructional videos, or answer questions. Among those social media, I especially like Live Mocha and Palabea.

Live Mocha provides learner incentives, Mocha and teacher points, for learning. For actively engaging in the site or completing course works, learners could earn Mocha points, and for helping other users with correcting, flashcards or translations, they could earn teacher points. With those points, users could enjoy more functions provided by the website.

In Palabea, learners could record their own video lesson and then upload to the site, which is also used in my class before knowing this website.

I think those two ides in Live Mocha and Palabea are also great for classroom learning. I have tried the later one for two semesters and receive great feedback from my students.