What's a trackback?
Peter writes in with a question that should have a very simple answer.
There at the bottom of every one of my posts (and at the bottom of many other blog's posts) you'll see the word 'trackback'.
Click on it and you'll see a list of other blogs that have commented on the posting. It's an effective way to encourage non-anonymous communication between blogs. It's also a good way to let someone find your blog... by posting your thoughts about blog posts that someone else is already reading... trackbacking your post to the original.
Unfortunately, it's not that obvious to use. You can see the wikipedia riff here.
First, if you've got blogger, you're out of luck. Most other kinds of blogging software permit it. Some do an autodetection, so once you start to do a post, it will enable you to just drag down and choose the post you want to track (details here: movabletype.org : TrackBack Explanation.) Others require you to hit the trackback button, copy the trackback URL you see right there, and then paste it into your post (in the field that says 'trackback field'.)
In Typepad, you'll find that field if you hit 'customize' on your post page. This is needlessly complex, but hey, it's not my fault.
Hope that helps.
[PS Douglas Welch says this will help for Blogger users.]