A lite version of The Buffy The Vampire Slayer RPG rules are available at the BBC, of all places.
A few years ago, I bought a box of Pokethulhu miniatures — little figures that look like Pokemons crossed with Cthulhuian Horrors. I had no idea that there also was a role playing game to go with it. And it’s free! Pokethulhu RPG.
Apathy: The Calling is a free roleplaying game of Cthulhuian horror. The author writes:
Welcome to Apathy:The Calling a Role Playing Game. In this game you play regular folk dealing with the mythos in the only way they can in the modern age, with apathy. As one of the select few for unknown reasons you can hear Dread Cthulhu as he dreams, calling you to commit unspeakable acts. Fortunately you�ve long been accustomed to ignoring inconvenient realities. You fight back with the inertia and apathy, that has defined you as a generation of slackers, miscreants, good for nothings, baby busters and losers.
Apathy, the Role Playing game is a game about the lost generation, everyday life and cthulhu.
RPG Now has a free horror RPG module called Dead of Night: Night of the Santa Claws. It’s designed for the Dead of Night RPG, but no doubt could be modded for any other system.