An example of how to give a WordPress plugin it's own URL/route

gistfile1.aw

<?php
/*
Plugin Name: redirect/routes test
Plugin URI: http://blog.enru.co.uk/2011-11-04-wordpress-plugin-with-own-url.html
Description: An example of how to give a WordPress plugin it's own URL/route
Version: 0.1
Author: Neill Russell
Author URI: http://www.enru.co.uk
License: Beerware
*/

add_action('init', 'my_rewrite');

function my_rewrite() {
    global $wp_rewrite;

    add_rewrite_rule('redir/$', WP_PLUGIN_URL . '/redir.php', 'top');
    $wp_rewrite->flush_rules(true);  // This should really be done in a plugin activation
}

add_filter ( 'the_content', 'content_filter');

function content_filter() {
        return 'beer';
}