FTP server?

What would be the simplest way to setup offsite storage that would function as a site for users to connect to so they can view .xls and .doc documents?

For example, my bosses asked me if there was a way they can have their managers just be able to view sensitive financial documents without having print/write privileges, while also setting up different user accounts in order to log activity.

I realize this is a rather broad question, but if you could just point me in the right direction that would be greatly appreciated. Thanks.