Google Apps are incredibly useful, particularly Google Docs. We used Google Docs this past summer for the Abydos Writing Institute. Our entire group of 20+ teachers was responsible for writing individual pieces and then publishing a compilation of all of our work towards the end of the Institute. Using Google Docs allowed us a quick and easy way to compile all of our work.
My kids have used Google Docs in the classroom, as well, during Banned Books week. In groups of 3, students collaborated on one document, chronicling their thoughts on certain banned books they were reading about on several different library resource websites. It makes it easy for me to track their process because I can see the timestamp of when they've last worked on their document. In terms of "due dates," this is nice to have. Not only that, but I don't have physical pieces of papers floating around my classroom or cluttering my desk (huge bonus).
I also use Google Forms when working on particular pieces of my ActivEducator position- as a way of chronicling broken ActivVotes and ActivExpressions, I must input numbers for other members of the ActivEducator community to see/take action upon.