After literally days of coding I have now completed --- well, stopped work on --- my new comment engine. What does that mean? Well, if you look down at the bottom of the page, you'll see a box where you can post comments on any of the Cowlark pages.
The comment engine is called Commentator, and is written in Java: it's a rather elegant combination of a front end using GWT, a back end using servlets, database storage using Berkeley DB Java Edition, and all being deployed on my solid-state ARM server using Winstone.
Interesting features include: all presentation is done on the client, which keeps server-side processing to a minimum; no templating or PHP anywhere; comment-enabling a page is as simple as putting one line in the HEAD element and two more where you want the comments to appear; proper support for rich text --- no nasty bbcode here; comments are emailed to me for moderation, which happens online via a (password-protected) public page... once the bugs are out I'm going to clean it all up and do a proper open source release of it.
Until then, feel free to let me know what you think.