Ad-hoc content access restriction is there a way to restrict content access to a specific subset of users upon node creation without having to create a specific user role and/or organic group?

For instance having a list of users to refer to upon node creation, and allowing ONLY them to view/visit/edit the node.
As mentioned above, the Node Access User Reference module does exactly that. You specify a list of user and grant them actions upon the node. Awesome.