I would look into Box.com which has been working to differentiate itself as being able to have audit logs, be things like HIPAA compliant, etc. They also had ro

I would look into Box.com which has been working to differentiate itself as being able to have audit logs, be things like HIPAA compliant, etc. They also had robust APIs last time I looked. There's also always AWS S3+AMI if you're willing to do more of the heavy lifting in terms of interface.