Virtual museums have been very popular since the early days of the World Wide Web and many scientific works have been published on this topic. Although the rich variety of possibilities for supporting collaboration among the users of virtual museums, today very few implementations offer support for such kind of activities. This paper aims at settling the value of collaboration in virtual museums by means of depicting and classifying collaborative organization and co-curation activities in establishing, designing, planning, realizing, operating, deploying and visiting a virtual exhibition applying action research. As a use case, we present ongoing work to realize a virtual museum devoted to Armenian cross stones (Khachkars).