A new application area for distributed systems evolves, driven by the need to support cooperative work. The importance of cooperative applications is demonstrated by the vast number of articles that have been published on this subject so far. There are two main streams of research: one being concerned with computer supported cooperative work and another dealing with the area of intelligent agents. This report gives an overview about tools supporting general cooperative work. To examine and compare current approaches, a detailed taxonomy of cooperation models and support tools is established and applied to existing systems. Based on the results of this classification, a new and general cooperation model is constructed. Furthermore, requirements for a universal tool to support cooperation are derived.