I've used Google Docs many times in the past. I find it useful when I'm working on writing assignments with others (specially if those who I'm working with are in another country). We have shared documents, edited them, etc. In addition, I've used it to share documents with my family in Argentina...we go back and forth at different documents, making changes, etc...so this is not only useful in my professional/student life, but also in my personal life.
I checked out Zoho Writer to see something new and different from what I'm used to. I personally like the fact you can access the docs from anywhere without having to save them on a USB flash drive, or email it to yourself...and I believe that since they (google, etc.) store them for you, it doesn't take space from your hard drive...That being said, we run the risk that they loose our docs and we can't retrieve them. Great week, I can't wait for the social networking piece next week :).