Argunet is the free, open-source, cross-platform suite for collaborative argument mapping. With Argunet you can reconstruct and visualise complex debates and argumentations. For teamwork, you can create your own project on the Argunet Server.
M. Northover, A. Boake, and D. Kourie. Proceedings of the 14th International Conference on Conceptual Structures (ICCS 2006), volume 4068 of Lecture Notes in Computer Science, page 360-373. Springer, (2006)