Do your players know all the rule books of your OSR game by heart, but you want to surprise them with a magic potion that is new to them? Do standard “regain x hit points” healing elixirs bore you? Are you looking for some potions that have a weird effect or a drawback? Something that you can put onto the shelves of a truly mad alchemist?
Gregorius21778: 50 Elixirs for "classic" RPG provides you with just that. The effects are far from mundane and next to all of the potions have drawback. The product was written to be compatible with "Lamentations of the Flame Princess"(tm), but should be compatible with most other OSR roleplaying games.