Google Apps gives everyone at your organization a custom email address, tools for word processing, spreadsheets and presentations, a shared calendaring system and access to a flexible intranet system. Standalone security and compliance services are also available.
The Standard version of the product is for free. The package includes:
Google Sites One-stop sharing for all types of team information
Google Docs Create and share documents, spreadsheets and presentations.
Gmail - Email with up to 6 GB of storage per custom email address, mail search tools and integrated chat.
Google Calendar Arrange meetings, set schedules, and publish event information.
Google Talk Instant message with co-workers and make PC-to-PC voice calls for free.
Start Page Preview your calendar and docs, add gadgets and search the web from one place.http://www.google.com/a/help/intl/en/admins/editions.html