Google Apps (service): What are the best practices and tools for backing up Google Apps (documents and mail) in a small business?

Google has done an excellent job of building this into Google Apps services so it isn't an issue for administrators. 

Google provides its own backup of your data as well as replication across servers in different data centers all over the world.  They even have tape backups of all data on top of other proprietary methods to secure your data.  You can see a video on data center methods to secure data here:

 

If your users change their work process in email and archive everything rather than delete it, this ensures all communications will be available and searchable.  Deleted emails are still located in the trash for 30 days, but with 7-25 gigs of storage, why delete anything?  It's been 6 years and I have only used up 18% of my 7 gigs on my personal account. 

All Google Apps Docs have built-in revision history too -with the ability to revert back to an earlier version that was correct. For the revision history of documents, in the documents file menu, select "See revision history". From there you can move the documents state back and even forward in time (up to the current revision).

Deleted documents are also placed in the "trash" where they can be retrieved within 30 days. Also, when sharing a document with other users, only the owner of a document has permission to delete it. If he is deleting something that is shared with others, a warning is displayed that others have access to the document and there is an option to leave it for those users.

Document owners can also transfer ownership to executives or administrators if the document contains vital information and an extra layer of security is needed to guard against deletion.