I am working on a set of spectral clustering methods that can essentially be used to detect a community structure in a social network. I tried this on a very small data set (Zachary's Karate club) that was available to me. I am looking out for some large networks where I can check the performance of the algorithm. I tried looking the SNAP(snap.stanford.edu) but not getting a data set that contains a well defined community structure. Is there any data set which I can use for my purpose?
The 'Social Network Analysis Interactive Dataset Library' at http://www.growmeme.com/sna/visual has over 150 datasets, and an ability to filter by size and whether community information is present (among other things).