UPDATE: now with link to the PhD thesis. By the time of blogging the thesis was not published. thanks to Patrick Durusau for pointing out the missing link.
One of the first things I did @ my Institute when starting my PhD program was reading the PhD thesis of Jérôme Kunegis. For a mathematician a nice piece of work to read. For his thesis he analayzed the evolution of networks. Over the last years Jérôme has collected several (119 !) data sets with network graphs. All have different properties.
He provides the data sets and some basic statistics @ http://konect.uni-koblenz.de/networks
Sometimes edges are directed, somtimes they have timestamps somtimes even content. Some graphs are bipartite and the graphs come from different application domains such as trust, social networks, web graphs, co citation, semantic, features, ratings and communications…
Jérôme also has calculated some metrics such as degree distributions and eigenvalue distributions for all these data sets and provides links to the sources. For most of the time he also states the paper for which these data sets have been created.
Over all the Koblenz network collection is a very nice data set for everyone who wants to do a PhD and wants to do analysis of graphs or do data mining or just needs some data sets for evaluation and testing! I am excited to see how this site will evolve over time and want to thank Jérôme for making this data available!