Dan Lewis has had an outstanding newsletter called Now I Know for quite some time. (In fact, I linked to one of his stories in #10 of my post "Ten for 110: Ten things you might not know about the Wright Brothers".) Although it's not an aviation newsletter, he covers an offbeat range of things in an engaging way. Occasionally, the odd and the overhead line up, as in "Where the Bags Go," an extremely interesting post on what happens to luggage that gets hopelessly lost.
While you're there reading that, you can sign up for his free newsletter to get more like that in your inbox. (You'll probably want to!) In fact, his newsletter is so good that he's turned it into a book, which is where the article originally comes from: