The usefulness of a syndication feed of your blog's comments
One of the accidental smart decisions that I made when I was writing DWiki's code for syndication feeds was that I should create syndication feeds for comments as well as entries. (This built on an earlier decision that I should have some way of getting a list of comments in chronological order, just as I had one for the standard wiki 'recently edited pages' feature.)
It isn't that I think this is an important feature to offer other people; as far as I know, none of the visitors to WanderingThoughts have ever paid it any attention. Instead, it (and the equivalent actual page) have turned out to be very handy for me, because it has two very useful effects. First and most obviously, it means that I can easily see all new comments to anything, anywhere, even if the entry is an old one. This is handy for more than the spam patrol, since every so often real people leave useful comments on old entries.
(It also drastically reduces any temptation to close old entries to comments, the way that some blog systems do.)
Second, I can shove the syndication feed into a feed reader and use all of the features to keep track of comments that need replies when I have the time and energy, or that I want to read carefully (or read what they've pointed me to carefully). This throughly beats all the alternate methods of keeping track of this stuff; if I had to do it by hand, I probably wouldn't do it at all.
(Of course, this doesn't mean that I actually write replies. As some people may have noticed, I'm generally terrible at writing comment replies that require substantive amounts of thought and effort, partly because of limited time.)