Using your google account to create student accounts.
Using Google Earth to teach area and perimeter. Great math lesson idea. The video isn't the best quality, but the idea is good.
Our City Podcast is a podcast for kids and by kids. Students from around the globe are invited to submit a recording all about the city they live in (with the help of their teachers or parents).
I love Google Notebook. If youv'e never used it before, this PDF document is a great read for learning the basics. Created by Wesley Fryer.
This could be a great method to use in wikis. Students will need a rubric for assessment as well as a means of being held accountable for what they learn from other groups presenting.