If you haven't looked at the site, SlideShare.net, it's worth some investigation time. Educators find it particularly useful because they can upload a slide presentation they have created and then narrate the slides to share with other folks all over the world.
Since our district is moving to Google Apps for Education district wide- it's been piloted at the middle schools for the past 2.5 years- I thought this slideshare presentation by Liat Rothfeld would be of interest in that it gives a nice overview of Google Docs and Google presentations. In it she also covers how to set up a personal Google account -which is optional. Users of amityschools.org will have accounts already established for them.
I have copied the embed code for the presentation, so enjoy.