a great idea, except that security bit against bots, also makes it impossible for blind people to use that site.

there is a similar attempt with www.gwap.com
(games with a purpose) - the idea is there are a lot of photos and say bits of music on the internet but not easily searchable since there is no other info attached to the pics.. or sound files.
so in gwap you compete with an unknown partner to describe a picture
and all the words that are in common are then associated with the picture..