Thanks to Jeroen for sending a link to this collaborative annotation service called A.nnotate. I suppose it's not quite crowdsourcing b/c there is no open call... so it's just collaboration... but the system itself is rather interesting and could be used to crowdsource. I write this as I'm wrapping up the back-end of our crowdsourcing micro-app for annotation & translation. Also in this category is ReFrameIt http://blip.tv/file/957958 - (the site seems down though... hope it's still around. A great idea).
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