When I saw the title of this article, my eyes lit up and I lit into the text. It provides some instructive commentary on what needs to happen in knowledge networks / communities / forums to encourage the participants' ongoing use. Ashley Bush & Amrit Tiwana, Designing sticky knowledge networks (pdf), Communications of the ACM, Volume 48, Issue 5 (May 2005). [Original CACM citation.]
Abstract: Much of any organization's experience and expertise remains underused and underexploited simply because it resides not in databases, repositories, or manuals but in the minds of its employees. Attempting to harness such distributed expertise, organizations have begun implementing collaborative knowledge networks---peer-to-peer digital networks connecting individuals with relevant expertise to their peers who need it. Unfortunately, however, successful knowledge networks represent the occasional island dotting a sea of failures. While many organizations are eager adopters of knowledge network systems, individual users frequently abandon them, leaving a trail of million- dollar paperweights. To be self-sustaining, knowledge networks must be sticky, though stickiness is an elusive design objective.
The authors surveyed several corporate systems in which people ask and answer questions from other employees. They looked at three aspects of stickiness: reputation, relationship capital and personalization.
Reputation is understandable: the more someone feels their reputation is attached to their participation in a knowledge network, the more they will continue participating. Relationship capital is their term for how strongly one feels connected to the community, and it possibly comes before reputation. In this case, the stickiness (the connection) has to do with how strongly one feels connected to the other participants in the network. If they've helped with problems, or if the participants have worked on other projects together, their likelihood for using the tool increases. While the study looked at online tools, these aspects apply to any kind of social network, be it within the company or your neighborhood. I wonder if there is a social aspect to these parameters: the sense of reputation or relationship capital is going to be defined by how the group works together.
These first two items are behaviors or traits of the people in the system, though the authors do make recommendations for building systems that highlight these aspects. The third, personalization, is more a feature of the tool. The authors found that too much personalization actually detracts from stickiness. They also differentiated between content and context personalization. I'm most familiar with context personalization: creating my own color scheme, user avatar and otherwise customizing my experience within the system. Content personalization
The authors suggested that personalization has a nonlinear relationship to stickiness. In particular, those things which can be easily replicated by other systems, such as content search strategies, detract from initial stickiness. On the other hand personalization that is unique to the system and helps the user feel more connected to the network tend to increase the desire to come back. The nonlinear nature is that content personalization becomes a desirable capability once users are already "stuck" and they need the system to provide them more focus and efficiency.
There are many other factors that one could consider in this kind of study, and given the authors' research areas I suspect there will be more in this vein.
There has been a recent thread in the blogosphere about the importance of purpose behind the social networking tools, in response to Five reasons social networking doesn't work from CNet's Buzz Report (Technorati cosmos for the article). Clearly, any tool, internal or external has to have some value or purpose, or it will die off. However, designers don't always know what they are building or how people will use it in the end. Thus, the need for flexibility and some level of openness. While corporate systems have a formal purpose, I am sure that there are many which end up as "million dollar paperweights" because they don't tie into the business drivers.