I am pleased to report that the Book of Lost Beasts and the Book of Lost Lore are now available to the general public in both print and pdf versions!
The Book of Lost Beasts has, of course, new monsters for your old-school game. Add angels, genie nobles, undead dragons, faeries, and many, many more creatures to your game.
The Book of Lost Lore has a variety of new races, classes, spells, and optional rules for your old-school game. Your players can be centaurs, jesters, mountebanks, and more. There are alternative combat and treasure systems, new magic items, a skill system, and much more. All are completely modular, allowing you to pick and choose what you want to add to your game.
You can buy the books here: