The Chronicles of Amherth is a campaign setting for Labyrinth Lord. The adventure Atarin's Delve is included as a part of the package.
So, what exactly do you get for your five bucks? In The Chronicles of Amerth, we get a setting based on (but greatly fleshing out) the Duchy of Valnwall that is included in the Labyrinth Lord core rulebook. I'd have to dig my LL book out to see just how close it hues to the original, but I suspect it's fairly close.
There's a twist on the magic using classes (that the GM is free to ignore) in that there is the addition of "Latent" magic. We are also given a chapter on Gods and Demi-Gods and another on the world history.
I like the use of a detailed Adventurer's Guild. It makes things a bit easier then using the usual tavern scene (not that I have anything against taverns) to give the PCs an adventure hook.
The Known World section details the continents of Amalor and Herth and the rest of the world. There is enough given to help the GM flesh out the world without block him into too much of a corner. Still, plenty (really - lots and lots) of plot hooks for each major location to make this the sandbox you want it to be.
Flora and Fauna gives us some useful flora for the PCs to use, or misuse. It also give us over 40 new monsters, which is a nice addition to the LL monster list.
Magical Treasures adds over 20 items to the LL's list of magic items.
We round things out with the continental maps.
Oh, and then there is the free adventure included in the mix.