Drupal 7 - key/value (machine_name/display_name) taxonomy term list

d7_keyvalue_taxonomy_term_list.php

function keyvalue_taxonomy_term_list($vocabMachineName){
  $tax = taxonomy_vocabulary_machine_name_load($vocabMachineName);
  $termTree = taxonomy_get_tree($tax->vid);

  $terms = array();
  foreach ($termTree as $idx => $term) {
    $terms[str_replace($vocabMachineName.'/', '', drupal_lookup_path('alias', 'taxonomy/term/'.$term->tid, 'und'))] = $term->name;
  }

  return $terms;
}

Returns an array of taxonomy term machine and display names for a given vocabulary machine name structured:
array(machine_name => display_name);