Google Image Labeler: Collaborative Tagging Game

Sounds interesting but here's what really caught my eye:

SearchEngineWatch dug out this excellent 51-minute presentation by Carnegie Mellon’s Luis von Ahn (also of CAPTCHA fame), who talks about ESP Game, which Google subsequently licensed to create Labeller. If you’re wondering whether the Labeller will help Google catch up on Flickr’s tags, here’s a salient stat from the video (8 minutes in): in one year, 9 billion people-hours are spent playing Solitaire; it took 20 million human-hours to build the entire Panama Canal - no wonder the professor talks about finding ways to optimise human cycles :-).

from Ajaxian