Amanda at Kiddio told me about LinkWithin. I think it's a pretty cool way to introduce your readers to posts that they may have missed. There are other "related post" tools, hacks and widgets out there, but this one's easy to use and easy on the eyes.
LinkWithi takes a square cropping of one of the images you've used in your post and puts it above the linked post title. You'll see a trio of them under each of your posts. The posts that the widget shows aren't quite random, which is nice. They're apparently selected based on popularity (comments, I'm guessing), relevance, and "recency." LinkWithin is not appropriate for blogs with time-sensitive posts (unless you delete all expired, etc., deals), since you don't want it displaying out-of-date links.
Here's what it looks like (courtesty of RookieMoms):
Check it out in action:
You can also find LinkWithin at the bottom of this post. After observing it for a few days here at BlogCoach, I'd have to say that LinkWithin does a decent job of selecting posts. A critique post, for example, brings up links to other critique posts. Right now I'm seeing three other "weekly widget" links beneath this post. Makes sense. Drawbacks? Longer post titles will be truncated, and sometimes the cropping of the images can be a bit odd. I'd also love it if I had a bit more control over which categories of posts were displayed.
What about you? Do you think this widget adds interest to BlogCoach? If you install LinkWithin on your site, leave a link so we can take a look!