For security reasons we'd like to see all documents in Google Drive which are shared with people outside the organization (Google Apps users). Is this possible? I know you can search for "to:[email]" but this requires knowing the exact email, we want "to:[non apps user]".
Google Apps does not natively support reporting on who has access to what in Google Drive. The report you are looking for is possible through a Google Apps script.
As you probably know, from the
If you are on the Google Apps Unlimited or Google Apps for Education license, you will have access to a Drive audit log, from which you may be able to generate a report based on sharing events. This could be cumbersome.
A free option based on Stefan Lasiewski's suggestion below is to try whohasaccess.com. The app requires