D6 - Trying to display variable_get()s in a block
You need to return the output of the block content as a string, not an array.

...
case 'view':
  $subject = '';
  $content = '';
  switch ($delta) {
    case 0:
      $subject = t('Subject in My Custom Block');
      $content =
        'blockvar_progress_so_far = ' . variable_get('progress_so_far', '0') . '&lt;br /&gt;' .
        'blockvar_number_of_projects = ' . variable_get('number_of_projects', '0') . '&lt;br /&gt;' .
        'blockvar_dollars_raised = ' . variable_get('dollars_raised', '0') . '&lt;br /&gt;' .
        'blockvar_number_children_impacted = ' . variable_get('number_children_impacted', '0');

      // Return values so they can be inserted into block
      return array(
        'subject' =&gt; $subject,
        'content' =&gt; $content,
      );
    break;
  }
...


See documentation on Drupal 6's hook_block() for a more detailed example.