How can the wordpress administration panel and the login page wp-login.php be hidden such that only the website administrator can access it? Can the URL be rewritten through some mod_rewrite rule without worrying about breaking anything (leaving aside all the plugins)? Preferably the solution should not be IP address based which will mean the administrator can access the website from only one or a set of computers.
Codex recommends adding HTTP authentication as additional layer of protection. Strictly speaking it doesn't rely on WP and keeping things independent is not a bad idea in context of security.