How many of you guys are communicating online with professors out of school hours?

Hey! I have a professor, who is in an attempt to make students enjoy learning, create some extra activities online. He reaches us with hot topics, ignites discussions, and even entertains us sometimes at evenings off. We treat him more like a mentor rather than a professor, because he cares about our personal and professional success.
Never thought, that extra work could be so rewarding and leads to mentoring provided by such a great professor.

So, do you communicate with your professors online? If so, what kind of activities do you accomplish?