One of the most important class of applications within the semantic web are services which help users to find out “hidden” relationships between resources like people, concepts or documents.
I´ve been trying out Google Sets from time to time which was an always impressive application to me. You enter one or more members (eg. persons, companies, technologies etc.) from the same class of your choice and Google “predicts” what else could fit into this set.
To me it seems like this service has been improved constantly in the last few months. If you type in just one member of an imaginary class like a person´s name you´ll see that Google has not only categorized search phrases but also knows a lot about social relationships.
http://labs.google.com/sets?hl=en&q1=andreas+blumauer – wow, Google knows a lot about my social network…