Format checkboxes/radio buttons into multiple columns

I love it when a quick Google search saves me an hour of writing my own code!
Thanks!

I got this working on my D7 site, with a bit of struggle. Here are the changes that I had to make to get it working:

• Modify function theme_multicolumn_options($element) to have these 3 new lines at the beginning:
  
  function theme_multicolumn_options($element) {
  // Modify to dig one layer deeper.  Not sure why original code didn't need this.
  $stripped_element = array_values($element);
  $element = $stripped_element[0];
...
• Also in the theme_multicolumn_options() function, comment out the theme() invocation, and replace with drupal_render():
  
  //      $output .= theme($type, $element[$keys[$current_option]]);
      $output .= drupal_render($element[$keys[$current_option]]);
  
  Without this, it was displaying only the checkboxes without their text beside them.

  With these changes, it's working great for me!

  Oh, and BTW, I'm using it with the Profile2 module, for a termreference fieldtype (lists a bunch of terms from a taxonomy for you to associate with your user account) in the "main" profile. Here is how I invoked the multicolumns, with hook_form_alter:
  

  /**
* Implementation of hook_form_alter()
*/
function MYMODULE_form_alter(&$form, &$form_state, $form_id) {
  if ($form_id == 'user_register_form' || $form_id == 'user_profile_form' && $form['#user_category'] == 'main') {
    $form['profile_main']['field_specialties']['und']['#theme'] = array('multicolumn_options');
    $form['profile_main']['field_specialties']['und']['#multicolumn_numcols'] = 4;
  }
}

  Ah, yes, that was one other change I made. I noticed that "#columns" was already in use, I think by profile2, so I renamed it to "#multicolumn_numcols". A corresponding change in theme_multicolumn_options() was to change the $total_columns line to:
    $total_columns = $element['#multicolumn_numcols'];

  So in the end, that function looked like this:
  

  function theme_multicolumn_options($element) {
  // Modify to dig one layer deeper.  Not sure why original code didn't need this.
  $stripped_element = array_values($element);
  $element = $stripped_element[0];

  // Initialize variables.
  $output = '';
  $total_columns = $element['#multicolumn_numcols'];
  $total_options = count($element['#options']);
  $options_per_column = ceil($total_options / $total_columns);
  $keys = array_keys($element['#options']);
  $type = $element[$keys[0]]['#type'];

  // Start wrapper div.
  $output .= '<div class="multicolumn-options-wrapper">';
  $current_column = 1;
  $current_option = 0;

  while ($current_column <= $total_columns) {
    // Start column div.
    $output .=  '<div class="multicolumn-options-column" style="width: ' . 100 / $total_columns . '%; float: left">';

    // Keep looping through until the maximum options per column are reached,
    // or you run out of options.
    while ($current_option < $options_per_column * $current_column &&
           $current_option < $total_options) {

      // Output as either check or radio button depending on the element type.
      $output .= drupal_render($element[$keys[$current_option]]);
//      $output .= theme($type, $element[$keys[$current_option]]);
      $current_option++;
    }

    // End column div.
    $output .= '</div>';
    $current_column++;
  }

  // End wrapper div.
  $output .= '</div>';
  $output .= '<div class="clear-block"></div>';

  return $output;
}