I didn't do this myself, but a friend of mine taught an online class in a distance MBA program.
For one activity, she had her students form negotiation teams (in her case, one group represented management, and the other the union). They were given a scenario.
Each team conferred via email (or other virtual communication methods) off the website, but would post a position/offer to the forum/discussion area. Then the other team would discuss their next strategy/offer/position among themselves, and post a counter offer.
This seemed to work well with her students.
Karen
http://karen.stanley.people.cpcc.eduCharlotte, North Carolina, USA