ACM-SIGMIS The ACM Special Interest Group on Management Information Systems promotes best-practice and research in the management of information systems and technologies and the use of these systems and technologies. SIGMIS is a founder of ISWorld Net at www.isworld.org, and a sponsor of several conferences on information systems and technology. Founded in 1961 as SIGBDP (Business Data Processing), SIGMIS is one of the oldest ACM Special Interest Groups, and for decades has been instrumental in defining and developing the field of management and information systems.
The Decision Sciences Institute (DSI). DSI is a professional organization of academicians and practitioners interested in the application of quantitative and behavioral methods to the problems of society.
Asia Pacific Region of Decision Sciences Institute (APDSI) APDSI is a sub-vanue of the DSI. The main objective of thie community is quite the same. However, the difference lies the scope of the problems of society. That is, while DSI globally deals with research agendas in terms of the problems of society, APDSI is geographically specific in Asian region.
I belong to ACM SIGMIS community mainly because my research interest lies in job burnout in IT workforce. Often time IT professionals, according to the human factor view, are being eclipsed by their technological artifacts; moreover, they are also viewed as functional, utilizable units which are embedded into such technology. This illusion has impacts toward all the stakeholders. The distorted images of IT professionals can mislead the IT managers to treat them differently. Such modern telecommunication technology renders IT personnel exposed to overwork. Support engineers, for example, are expected to be on-call in order to respond to any request of service 24 hours a day, IT people feel overwhelmed by demands of support jobs. Since an organization increasingly employs technological equipments, the demands of supports of course grow in parallel manner.
DSI and APDSI is very attractive to me because these two venues just focus on the very pressing global agendas regarding ICT development. Information has price, and ICT has been regarded an active economic commodity, and this commodity could make a great effect in developing world. Therefore, it is very important for developing world the exercise the right ICT policies to economically, socially, and technologically improve them.

Suwan, I think I share some interest with you. If you are interested in decision sciences, I strongly recommend you to read papers by experimental economists in University of Chicago and some law & economics papers. Law & economics is one of the fields where objective decision making becoming more and more important with the criticism of subjective judgement.