WordPress.org

1. Install the plugin and activate
2. In a post or page, type [external]/path/to/your/script.txt[/external]

Examples:

[external]/path/to/file.php[/external] [external]http://my.website.com/about.html[/external] [external start=10 end=20]/very/long/script.js[/external] [external format=xml]/not/really/a-php-document.php[/external]