Depending on the campaign, I develop quite a bit of detail on some aspect of the Majestic Wilderlands. For one campaign I fleshed out the details on the religion of Silvanus the Forest Lord. Then last year for the Gold Star Anime campaign I turned it into a booklet for one of my players. Last week I realized that I never posted it for the rest of you to use.
You can download the Gods of the Majestic Wilderlands, Silvanus from here. It also includes the relevant information from the Majestic Wilderlands for Swords & Wizardry.
One interesting thing about this particular bit of writing is that highly modified it served as the basic background of the NERO LARP chapter I ran a few years back. I got rid of the religious aspect and focused on the the rangers. Creating a code to express the philosophy of the Rangers. The players liked it a lot and more than a few of them decided to become members of the Rangers. You can download the packet from here.