Author: J.Sniderman (4 Mar 10 2:57am)
Depending on your hosting setup, you may be able to firewall them out entirely. *If* you have root access to the machine (your own server, vps, dedicated etc) outright firewall them.
I've done this on very rare occasion, once involving a former girlfriend, and a couple other times with random spammers. Nothing says "go away" like a big old "Page cannot be displayed" or "Firefox cannot find the site" that noone else is faced with.
Another nice option, is using .htaccess, redirect them to a specific other page. This can be a generic "banned" page, something more hostile, even a mirror of the original page, but with all emails and commenting options disabled.
Also, make sure you are logging the referer headers. I had one instance of a group of 3 such trouble makers who all came from the same URL, which it turns out was a post on their own healthcare intranet site (yes, i was spammed by an actual doctor once, long story, he thought my opinons were harmful to his 'cause') with a link to me, and instructions to their employees to poke around and make trouble. Once armed with such information, you can more effectively block users proactively, and helps to understand exactly who the enemy is, and as in my case, if they leave such pages unprotected, what their entire strategy is.