You can create collaborations within your groups using Google Docs.
Note: At this time, Google Docs are the only service supported through Collaborations.
Create Collaboration Document
To create a collaboration document using Google Docs, you will first need to name the document , create a description , and select who you will be collaborate with . Click the Start Collaborating button  to create the document.
Note: Google Docs allows you to add up to 50 users per collaboration, and all users can view and edit a document at the same time.