To get an overview, start with Welcome to Google Apps
The following are a series of short training films on how to use the different apps in Google Apps for Education. Please note as well that Google Apps has a channel on YouTube with current material and videos at http://www.youtube.com/user/GoogleApps
Gmail:
Overview of Gmail in Google Apps
Threaded Conversations in Gmail
more Gmail training videos are located at http://www.youtube.com/view_play_list?p=8A0C9023238F7724 and http://www.youtube.com/view_play_list?p=29CB32DA076AB3D2
Calendar:
Schedule a Meeting in Google Apps
Sharing a Calendar in Google Apps
more Calendar training videos are located at http://www.youtube.com/view_play_list?p=86393B62706987AD
Documents or Google Docs:
Auto-fill cells in a Google Spreadsheet
Revision history in Google Docs
more Google Docs training videos are located at: http://www.youtube.com/view_play_list?p=372A76C86AF35D52
Sites or "build your own website":
Display a calendar in Google Sites
More Google Sites training videos are located at: http://www.youtube.com/view_play_list?p=CB91CEDD85EF4730
Sampling of websites built in Google Sites:
This site :)
Google Talk:
These videos were created by Google and are on YouTube but are posted on this site as a convenience to GTS students.