Treat your place like your home: welcome people, fix them a drink and make them feel comfortable. Before you know it, your guests will be chatting amongst themselves, the party will be pumping, and people will be making plans together.
Ciro Cattuto wrote a simple piece of code that builds and visualizes a network of inferred semantic relations among the tags that Flickr users attach to their photos.
J. Leskovec, L. Backstrom, R. Kumar, and A. Tomkins. KDD '08: Proceeding of the 14th ACM SIGKDD international conference on Knowledge discovery and data mining, page 462--470. New York, NY, USA, ACM, (2008)
R. Kumar, J. Novak, and A. Tomkins. KDD '06: Proceedings of the 12th ACM SIGKDD international conference on Knowledge discovery and data mining, page 611--617. New York, NY, USA, ACM, (2006)