Access custom user field from a different account
This seems a bit dirty, but using your exact code as a base, something like the following may work:

$uids = array(
  // Here is the list of user ID's that you know.
);

$full_names = array();

foreach ($uids AS $uid){
  $account = user_load($uid);
  $full_names[$uid] = $account-&gt;field_full_name[LANGUAGE_NONE][0]['value'];
}

unset($account);

return $full_names;


This will give you an array of full usernames keyed by the UID.

Also to bear in mind, this performs no access checking or permission checking.

For further reading, you might want to try taking a look at something like field_get_items() as well.