I have recently completed MIT xPRO's 4-week online course in Negotiating to Create Value - The Mutual Gains Approach.  This not only taught theory but enabled us to put this knowledge into practice by role-playing with our peers online.  One of the negotiations was with a mediator and lawyer in Portugal, and another was with corporate executive in the US.

The faculty director is Professor Lawrence Susskind, who is a co-founder of the inter-university Program on Negotiation at Harvard Law School (PON).  

The course had a different emphasis to the Yale course I took during lockdown, and given Professor Susskind's legal background compared to Professor Nalebuff's business background, this perhaps isn't surprising.  Having studied with Harvard's PON in 2017 I felt that the Harvard and MIT courses complemented each other well.

As a mediator and a dispute resolution/litigation solicitor, I felt that the course was valuable in both spheres.