Custom Fields to display website name and URL

I would like to be able to use custom fields to display a list of associated websites that belong with a particular post

This displays the keys:

<?php
  $custom_field_keys = get_post_custom_keys();
  foreach ( $custom_field_keys as $key => $value ) {
    $valuet = trim($value);
      if ( '_' == $valuet{0} )
      continue;
    echo $key . " => " . $value . "<br />";
  }
?>

I know this displays the keys from the meta data, but I want to able to display both the keys and the values in a particular way.

Something like this, but its not working for me:

<?php
  $get_post_custom($post_id);
  foreach ($key && $value) {
     if ( '$key' != 'keywords' || '$key' != 'description' || '$key' != 'title')
      continue;
<a href="<?php echo $key ?>"><?php echo $value ?></a>
  }
?>

(I am also trying to exclude 3 types of meta data from being displayed)

I know I’m way off here, but I wanted to give an example of what I’m trying to accomplish.

Any help would be greatly appreciated!