Singleton template I'm currently using to namespace stuff.

singleton_template.php

class My_Singleton {

  /**
	 * The only instance of the My_Singleton Object
	 * @var  My_Singleton
	 */
	private static $instance;

	/**
	 * Returns the main instance.
	 *
	 * @return  My_Singleton
	 */
	public static function get_instance() {
		if ( ! isset( self::$instance ) ) {
			self::$instance = new My_Singleton;
			self::$instance->setup_actions();
		}
		return self::$instance;
	}

	/**
	 * A dummy constructor.
	 *
	 * @return  My_Singleton
	 */
	private function __construct() {
	}

	/**
	 * Set up WordPress hooks
	 */
	function setup_actions() {
	}

}

/**
 * Gets the main My_Singleton Instance
 *
 * Calling this function places into motion the main functions of the class, but can also be utilized to get properties
 * and run methods of the class.
 *
 * @return My_Singleton
 */
function get_my_singleton() {
	return My_Singleton::get_instance();
}

add_action( 'init', 'get_my_singleton' );