The system don't really support what you ask for, but you could use the following setup:
Make a content-plugin (http://docs.joomla.org/J2.5:Creating_a_content_plugin). In the event onContentPrepareForm, you modify the created_by_alias-field to use it for your special user allowed to view this content article.
function onContentPrepareForm($form, $data){
// first check that context is right
// Then change the type of the field. This should allow to select
// the user when you create the article.
$form->getField('created_by_alias')->__set('type', 'user');
}
In the event onContentPrepareData, check if the data in the created_by_alias references a valid user in the user group your users shoud be in
public function onContentPrepare($context, $article, $params, $page){
// first check that context is right
//Then fetch the user data:
if(is_int($article->created_by_alias)){ // ( Optionally check if the article is in a specific category )
$db=JFactory::getDbo();
$currentuser=JFactory::getUser();
$allowedgroup=2; // the registered users group
$sql="select u.id from #__users inner join #__user_usergroup_map ug (u.id=ug.user_id) where ug.group_id={$allowedgroup}";
$db->setQuery($sql);
$user=$db->loadObject();
if($user->id==$currentuser){
$data->user=$user;
}
else{
//Unset the article content to prevent unothorized users from seeing the content.
unset($article);
}
}
Finally, create a module (http://docs.joomla.org/Creating_a_simple_module) that feeds articles for a particular user, containing at least:
$list=array();
$user=Jfactory::getUser();
if($user->id>0){
$sql="select * from #__content where created_by_alias={$user->id}";
// ( also add sql to check that the user has access,
// the article is published, the correct category etc)
$db=Jfactory::getDbo();
$db->setQuery($sql);
$list=$db->loadObjectList();
if(!count($list)) return;
}
else return;
print_r($list); // Prints the content articles
This scheme should protect unauthorized users from viewing the content of the articles ment for a specific user. The module should (after nicely outputting what you want to display) display a list of articles for the logged inn user. The module can link to the article in the normal way, and the authorized user will have access. So it should be "safe enough", and provide the functionality you need without too much hassle.