There are many ways to use Google Docs and its sharing settings for collaborative work. Below are just a few of the ways I've used it.
Shared notes at a conference.
Drafting a document with others.
Asking for comments, suggestions, ...
Publishing content to the web and embedding it on webpages like tosachat.org.
I recently came across this website of tips and lessons on using Google Apps. A lot of the information is basic to me now (thankfully), but definitely still useful.
Here's a question I still have though - about tables in Google Docs. Is there a setting or way to make table cells that reach the bottom of the page not spill the text onto the next page? I want the cell to automagically start on the next page instead.