I'm currently working with two clients who both wish I could give them more levels of read protection on posts and pages.
Right now posts can only be public or private and stock behavior is that a user has to be an editor or administrator to see Private posts and pages. Essentially, I'd like to be able to mark, posts public, subscriber, contributor, author, editor, or admin, and have each corresponding role be able to see posts & pages assigned to their role and the roles below theirs. So, the higher up the admin chain you are, the more levels of content you can see.
I am currently using the Role Manager plugin and my interim fix is going to be to let subscribers see private pages and let contributors see both private pages and private posts.
I know that pages & posts can also be password protected, but that is not as elegant because they are not hidden from users who can't access them, and they require a login for each one. It would be much better if there could be more levels of Private posting.