Google Docs- Document Sharing

I think using google docs is a neat idea. I do like that we can share ideas with others. I think my students would like adding on to a story. I have done that kind of assignment with a small group on paper and it has been fun. Another idea would be to add onto a sentence. My third grade students choose to write short sentences, for example, The car sped. They could then add adjectives and adverbs. This way I could see if they know what an adverb and adjective is when they add to simple sentences.
I'd like to hear other ideas as to how to use this feature.