Node Access User Reference | drupal.org

Allows you to configure a CCK user reference field so that the user whom is referenced in a node is granted access to view the node. There are also options to give the user access to edit or delete the node.

This is great if you want your node authors to be able to choose additional authors, or choose who can view their node, as well as being able to display the list of authors or viewers in your node, or in Views. If you just need to administer view/edit grants on nodes without the CCK field you should use the Nodeaccess module.

Please note that this module will remove the default view access people have on a node - you will need to use a different Node Access module to grant default access to users. I recommend doing it by taxonomy, or per node.