Each application that is free on the Internet can be useful for blended learning. It all depends on your resourcefulness and willingness to use them. In my lecture I use the Messenger, Dropbox, SMS, Facebook, and other free sources on the Internet.
I have an interesting book I think that could help you.
Social media is fractionally efficient in the teaching and learning processes. It is proficient only in developed countries with an uninterrupted power supply and access of both the learners and the instructors to gadgets that will function such platforms. Excellent internet facility would be an added advantage.