Okay...now this is something I already know about and use A LOT! I have an iGoogle page that includes news, a calendar, NatGeo photos, etc. I've also used Google Docs on a number of occasions--Google Docs are a great way to share all kinds of documents.
I've also played with Google Earth...it's really fun to search for different places around the globe. And, I have a Google group (private) for my Junior Achievement students at school. We're just now getting it organized, but I believe it will help us to communicate more effectively.
The one aspect that I wasn't familiar with was Google Notebook. It took me a few minutes to figure it out, but I like it. It will make Internet research much easier to organize. In fact, part of my curriculum requires several of my classes to conduct Internet research. I think introducing my students to Google Notebook would really help them organize and catagorize their research.