Problem Sending data send to a block
Use hook_block_info and hook_block_view. Something like this:

function MYMODULE_block_view($delta = '') {
  $block = array();

  switch ($delta) {
    case 'my_block':

      $blockContent = '&lt;p&gt;Nothing to show&lt;/p&gt;';

      // assuming we're getting it from POST but the source can be whatever you want
      if (isset($_POST['key']) &amp;&amp; null != $_POST['key']) {
          $blockContent = '&lt;p&gt;' . $_POST['key'] . '&lt;/p&gt;';
      }

      $block['subject'] = t('My Block Title');
      $block['content'] = array(
          '#markup' =&gt; $blockContent
      );
      break;
  }

  return $block;
}