How do I show the last created node in a block, without using Views?
The recommended way would be to create a custom module that will find/load the node and display in a block. Assuming Drupal 6 from your previous questions.

In your custom module:

&lt;?php
/**
 * Implementation of hook_block()
 */
function YOURMODULE_block($op='list', $delta=0, $edit=array()) {
  switch ($op) {
    case 'list':
      $blocks[0]['info'] = t('Last Node Created');
      return $blocks;

    case 'view':
      // Get the last created node
      $nid = db_result(db_query('SELECT MAX(nid) AS nid FROM {node}'));
      $node = node_load($nid);

      // Add subject/content to block
      $blocks['subject'] = t('Last Node Created');
      $blocks['content'] = theme('YOURMODULE_node_last', $node);
      return $blocks;
  }
}

/**
 * Implementation of hook_theme()
 */
function YOURMODULE_theme() {
  return array(
    'YOURMODULE_node_last' =&gt; array(
      'arguments' =&gt; array('node' =&gt; NULL),
    ),
  );
}

/**
 * Create the HTML output for last created node
 *
 * @param $node
 * Node object for last created node
 */
function theme_YOURMODULE_node_last($node) {
  // Insert theming code here...
}


For more information on creating custom modules, see the Module developer's guide.