I’ve made you a cookie. Or a Greasemonkey script, anyway.
Install the script, then go to Manage User Scripts in Greasemonkey. Click the Options button under the script, and then click “Edit this user script”.
At the top of the script, you’ll see the following line:
var ignore_list = new Array("Poster1", "Poster2", "Poster3");
Replace Poster1, Poster2, etc. with the names of the posters you wish to ignore. You can add as many as you like, just be sure to wrap the usernames in quotes and separate them with commas.
Once you’ve added users to the list, the script will block:
[ul]
[li]Posts by those users[/li][li]Posts that quote those users[/li][li]Threads started by those users (in the forum listing)[/li][/ul]
It will remove them entirely; there will be no “Show this post”-type buttons, so the only evidence that they ever existed will be the fact that there are fewer posts/threads on the page than there ought to be, and the post numbers will skip. This is a design feature intended to more thoroughly eradicate the object(s) of your ire from your awareness, and not at all functionality I was just too lazy to add.
Enjoy! 