Thing 15 is all about Google Docs. Google docs was born largely when Google bought Writely. Basically, Google Docs is an on-line Microsoft Office suite. There are really big differences, but it's a simple way to understand what Google Docs is all about. With Google Docs, you have access to a word processor, a spreadsheet program, and a presentation program. All are much more basic than programs that live on your computer, but they are all functional. There are also some benefits. For example, you can easily share your documents with whomever you want. Both of you can work on the documents at the same time.
Google now has an offline component. I've never used it so I'm not sure how well that it works.
I've used Google Docs for quite a little while now. Shawn and I use it for show notes. That way, either of us can add to the notes throughout the week. When we're ready to podcast, we've got the same notes in front of us.
Some districts block Google Docs. Check before you plan on using it.
Google Docs would be used largely like Wiki's.