There are many features to explore, so we encourage you to check out the following information:
Email Video Overview - http://services.google.com/apps/resources/overviews_breeze/Mail/index.html
Google Apps Help Center - http://www.google.com/support/a/users
Each service in Google Apps has a comprehensive help center (Gmail, Calendar, Docs, etc.)
Visit End User Help Centers for solutions to common questions
Google Apps YouTube Channel - http://youtube.com/googleapps