You may see a widgets on profile page sidebar like friends, photos. You can use this hook to add new module content.

<?php
function my_component_init(){
		ossn_add_hook('profile', 'modules', 'my_component_hook');	
}
function my_component_hook($hook, $type, $modules, $vars){
		//$vars['user'] contains user instance (OssnUser)
		//we extend exsting modules array
		$modules[] = 'new module contents';
		return $modules;
}
ossn_register_callback('ossn', 'init', 'my_component_init');