//display a starting list of popular categories
function showCategories($mode)
{
  global $categoryList;
  echo '<hr /><h2>Selected Categories</h2>';
  
  if($mode == 'books')
  {
    
    asort($categoryList);
    
    $categories = count($categoryList);
    $columns = 4;
    $rows = ceil($categories/$columns);
    
    echo '<table border ="0" cellpadding ="0" cellspacing="0" 
                 width ="100%"><tr>';
    
    reset($categoryList);
    
    for($col = 0; $col<$columns; $col++)
    {
      echo '<td width = "'.(100/$columns).'%" valign = "top"><ul>';
      for($row = 0; $row<$rows; $row++)
      {
        $category = each($categoryList);
        if($category)
        {
          $browseNode = $category['key'];
          $name = $category['value'];
          echo "<li><span class = 'category'><a href = 
                 'index.php?action=browsnode&browseNode=$browseNode'>$name
                 </a></span></li>";
        }
      }
      echo '</ul></td>';
    }
    echo '</tr></table><hr />';
  }
}