Snapchat is becoming an increasingly popular place for me to send my blog visitors to, and I think a Messenger button (for Facebook) would be a really highly converting social share button. Also after F8, Facebook have opened up the Messenger API for businesses to create powerful experiences within Messenger. I can foresee it becoming a popular contact channel in the near future.
Potentially an iMessage/SMS button for social sharing would be worthwhile too.
Is there a way I can add these myself, or alternatively would you consider adding them?