I have used Google Documents in a research setting, where I had to send an article between colleagues and supervisors for editing. Google Documents is very useful in this sense, as it allows for comments and alterrations. Claire had a really great idea of using GoogleDocs to create a form which we could then fill in. Read her investigations of GoogleDocs here.
I have also signed in with my Google ID to use ThinkFree, which is similar to MS Office in function and format. It reminds me of OpenOffice, which is also uses Java and, like GoogleDocs and ThinkFree, can be used as an "Office in the Clouds" (Cloud Computing, that is) for sharing and editing documents between colleagues.