As one of the datasets he used http://www.livejournal.com which is can be freely crawled. This is an interesting resource for doing research on social networks.
As part of his dissertation project he implemented several applications. I found the following two remarkable and very useful:
- http://www.confsearch.org Looking for conference based on keywords? Searching for a conference in a field? Which conferences are related? Have a look and you will find some answers.
- http://www.museek.ethz.ch a comprehensive mobile music application for Android.
 Goussevskaia, O., Kuhn, M., and Wattenhofer, R. 2008. Exploring music collections on mobile devices. In Proceedings of the 10th international Conference on Human Computer interaction with Mobile Devices and Services (Amsterdam, The Netherlands, September 02 - 05, 2008). MobileHCI '08. ACM, New York, NY, 359-362. DOI= http://doi.acm.org/10.1145/1409240.1409288