My ultimate .htaccess file for CodeIgniter 2.0
#Initialize mod_rewrite
RewriteEngine On
RewriteBase /
#Force "www" subdomain
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]
#Re-route forbidden urls
RewriteCond %{REQUEST_URI} ^(system|application).* [OR]
RewriteRule ^(.*)$ index.php?/$1 [L]
#Re-route urls if file/directory does not exist
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?/$1 [L]