The principle developers of Habitat, a "multi-user online environment" write about their experiences and lessons learned. Habitat was a virtual community that can be thought of as a very early precursor to Second Life. In the paper, the authors declare some guidelines for social software, some of which are widely accepted today. Some of the guidelines, such as the assumption that bandwidth will always be a scarce resource, were prescient. The authors spend a lot of time trying to say, I think, that complexity in social software should come from the users, not the programmers.
In another feat of foresight, the authors warn administrators of social software to try to "work within the system". I've seen a good number of social apps get a lot of negative attention when they censored a user's action for reasons that seemed unjust. Flickr and Digg come immediately to mind. The authors might have recommended that the moderators of flickr and digg attempt to discourage unwanted behavior without pulling the adminstrator card and wiping out user content.
Like the LambdaMOO paper, there's an implicit warning against assuming any sort of higher-mindedness from the users of your software. Assume that online identities will display every baser behavior that offline humans do. The authors remind us that real people are behind those avatars.
There's also an extensive bibliography at the end of this paper, although the listed material is by now quite dated.