A plugin to reject comment submissions that contain links with them.
Place the no-links.php file beneath wp-content/plugins, and activate
it via your admin panel.
(If you prefer you can clone this repository beneath wp-content/plugins
instead.)
Once activated comments that have been submitted with an URL/website link will be marked as spam automatically, post-submission.
My [http://blogspam.net/](blogspam service) will do a far better job of blocking comments, and there is a wordpress plugin available for it..