Facebook, Google+, Vine, Instagram, musical.ly, Youtube, iFunny, Twitter, and whatever else comes along that catches my interest.
Did Snapchat about three years ago but got to be too much to keep up so I stopped.
Did Skype up until 2.5 years ago. Same reason. [too much to keep up with].
Did Kik until two years ago until too much to keep up with.
In fact, I pretty much abandoned all private-ish social media to stay focused on public stuff. Keeps me from getting in to time-sucks with small circles of people.
Vine’s a favorite ’cause it’s quick. Made 15,000 of them so far.