Harvesting facts from Web sources has primarily been through the use of semi-structured corpora, such as Wikipedia, and information extraction techniques from textual sources. But, the problem of coverage and accuracy of facts remains. Human-computing is a promising paradigm for getting humans to do tasks that machines find difficult. HC games like ESP, Verbosity and PageHunt have been built to deal with computationally complex problems through human collaboration in an online game-play environment. Using world wide web as a source for knowledge, we pursue designing games on the basis of this paradigm to collect a large number of new facts and verify the accuracy of existing facts in an automatically constructed knowledge-base.