An unexpected dividend from the Enron scandal: the corpus of emails turned over to investigators by the dodgy energy-trading company (which, in this case, includes everything ever emailed through enron.com)
fell into the hands of academics and has since proven to be
a boon to social network researchers.
Some of the methods in the paper (i.e., automatic community detection) look useful; it'd be interesting to apply them to, say, LiveJournal, Flickr or even inter-blog links.