Here's my first WordPress Plugin: the Dubyalizer. You can use it to mock a troll by changing every instance of the letters R or L in their comment(s) to W.
It's basically nothing but a slightly-tweaked version of the classic Disemvoweler plugin (by Ryan Boren/Mark McIntire).
Props to hanumizzle for the idea.
Simply drop the file dubyalizer.php into wp-content/plugins/ and activate it from your WordPress admin interface.
(You can download the file by right-clicking on the link in the paragraph above.)
To dubyalize an individual comment, just insert the string [dubya] at the very beginning of the comment. The troll's name will be changed to "Troll" and his/her website URL will be removed.
If you have a persistent troll, you can add his/her IP address to the blacklist (it's hard-coded in the PHP file, so you'll have to edit the file by hand and re-upload it to your wp-content/plugins/ directory). Comments posted from blacklisted IP addresses will subsequently be dubyalized for you automatically.
Send email to dpf at dumpendebat dot net.