Just been made aware of this
http://www.zooniverse.org/
via
http://ancientlives.org/
and Today on Radio 4.
Not a wiki, but I thought is might be of general interest.
I find these projects fascinating - particularly because they make it really
easy and interesting for people to make small contributions... rather better
than the Wikimedia movement does!
My girlfriend classifies galaxies on Galaxy Zoo all the time, but she finds
Wikipedia too big and intimidating to make the smallest correction to.
"Gamification" is a bit of a buzzword at the moment - possibly an over-used
one - but these kinds of projects are very good at it.
Chris