Two OCR correction games were developed within BHL (a collaboratiion among Cornell, Harvard, the Missouri Botanical Garden and the New York Botanical Garden).
Smorball (http://smorballgame.org) is fast-paced.
Beanstalk (http://beanstalkgame.org) is leisurely.
Both can be hosted and run for other OCR correction projects. Instructions are on the BHL wiki (linked above).