I've made a webquest about the 7 wonders of nature with Google Educational Apps:
Students all over the world can join this webquest by making a Google Doc about their favorite wonder of nature. This Google Doc can easily be integrated in this webquest. The product of the webquest can therefore been seen all over the world.
I've tried to encourage students to use all sorts WebTools. I've made a example of such a nature-doc at:
For Dutch students (10 - 15 years) I've made a webquest where pupils from different schools work together on a part of a website about China. This is also done with Google Docs.
I think that WebQuests are one of the best ways to do collaborative learning and Google Docs make it possible to easily work together.