A number of recent posts have discussed examples of technological compatibility in terms of network effects. beata385 and njr25 each discuss HD DVD and Blu-Ray, while brucelee26 considers the transition from Windows XP to Vista — an interesting example, since instead of two competing firms, we have a single company trying to shift its users from one technology to another.

Several posts have discussed examples drawn from biology. harapalb discusses the cascading effects of extinctions in an ecosystem. The article cited in the post is an example of work that treats food webs as complex networks — roughly, introducing nodes to represent species, and links to indicate that members of one species consume members of another. See for example the recent papers of Neutel et al. (2002) and of Williams et al. (2002).

In a different connection to biology, Spero discusses the enumeration of network motifs — particularly, the way in which the relative abundance of small subgraphs can provide global information about a network. This idea has been applied to networks across a range of areas, but it has been perhaps particularly informative in analyzing networks that encode cellular metabolism. One of the more heavily-cited papers to promote this idea is Milo et al. (2002).

A number of posts have continued to identify further interesting examples of population-level feedback effects in various settings, including college rankings, pop music, political primaries, the Web site StumbleUpon, and marketing via word-of-mouth effects and identification of fashion leaders.

Finally, as pointed out in a post by adrian, last Sunday’s New York Times Magazine article by Duncan Watts is a nice overview of a number of themes from class over the past few weeks.