GeAnn

GeAnn is a crowdsourcing-powered Web game for collecting document relevance judgements.
Crowdsourcing for academic and industrial purposes often faces issues of quality control and worker motivation. GeAnn offers an alternative that focuses on entertainment as an alternative incentive. Tasks such as document relevance assessment or image clustering can be represented in game form to achieve comparable label quality at significantly lower cost and high user satisfaction.

Citing:
If you use GeAnn, please refer to C. Eickhoff, C. G. Harris, A. P. de Vries and P. Srinivasan. "Quality through Flow and Immersion: Gamifying Crowdsourced Relevance Assessments". In SIGIR 2012