Disqus comments
I used to think that if I did my own thing to handle comment spam then I'd be low-hanging fruit and wouldn't have a problem. And this worked for quite a long time. But a couple of weeks ago it stopped working, and last week I turned off comments on jerakeen.org just so I didn't have to delete 30 spam comments every day. And I'm far too lazy to do anything properly to solve this.
Fortunately, Disqus have appeared recently, and they're great. I can just embed someone else's commenting framework and let them deal with the problem. The obvious downside is that the comments aren't 'really' on my page, so I won't get any google juice from them. But on the other hand, the comments aren't really on my page, so noone else will get any google juice from them. Maybe this'll make them less appealing as a spam target in the first place.
The other downside is that there's no import capability for my old comments. I've settled for just displaying the old comments in-place, with Disqus comments under them. I've also take the opportunity to make it slightly clearer when I'm syndicating comments from flickr rather than allowing them on the local site. I haven't managed to combine the count of old and new comments yet, but I'm sure I'll get it soon. Until then, pages with old-style comments will just have 2 figures for comment count. You'll live.