OntoTube is a two player quiz game for annotating videos. Both players have to answer questions about the video. The answers they provide are used for data generation.
DBpedia is a community effort to extract structured information from Wikipedia and to make this information available on the Web. DBpedia allows you to make sophisticated queries against Wikipedia, and to link other data sets on the Web to Wikipedia data.
M. Knuth, J. Hercher, und H. Sack. Proceedings of 2nd International Workshop on Usage Analysis and the Web of Data (USEWOD 2012), co-located with the 21st International World Wide Web Conference 2012 (WWW 2012), Lyon, France, (April 2012)