Oh my gosh! How more cool can word processing be than this? Although I have been using Google Docs (formerly Writely) for a while and loved its functionality and features, yet I just discovered a feature I have not used before and it turned out to be really cool.
Google Docs allows you to see past versions of your document. You do not have to setup anything or configure it to do so, it does so by default! At any given time, you can go to your document and see past "Revisions" of it. It's like a time machine where you can go back in time. It's a really really cool feature that is not only cool but actually useful.
To use this exciting feature in Google Docs, all you have to do is open a document then click on the Revisions tab. Then select any point in time, in the past, and you will find in front of you how the document changed since that time! Amazing!
Kudos for you Google again and a gain.