DriveThruRPG's Halloween "Treats". I ended up choosing Goodman Games' free offering of Dungeon Crawl Classic #24: Legend of the Ripper.
Seriously, if you are even thinking of getting this adventure, ACT NOW!!! It is only free through the end of the day.
The DriveThruRPG listing says it is a D&D/d20 adventure, but the title shows it as a Dungeon Crawl Classic adventure, which is an actual recognized game system at DriveThruRPG, unlike my beloved HackMaster.
I'm not quite sure where it fits*, but I think it is intended to be a d20 game since it was put out in 2006. I think the name was lifted from the adventure series to use for their game system. At any rate, it is a minor point for me because the little corner tag on the cover sums it up well enough: "ALL NEW MODULE FOR ANY FANTASY CAMPAIGN".
I'm not playing a d20 game so I'll have to adapt this adventure for use in my game, but since I'm going to have to tweak the story just a smidge, I'm up for larger tweaks. I love the way that Goodman Games sets up these Dungeon Crawl Classics adventures for tweaking, actually giving some instructions and help with layout.
Starting out with an introduction and summary, the adventure goes right in to adapting the plot. The GM section is filled with great info to record your tweaks and even goes so far as to make suggestions on how to scale the adventure up or down for weaker or stronger parties. The suggestions aren't simple swap-outs either, but some story-driven adjustments. The adventure also give some great suggestion on how to deal with imminent PC death as well as some special effects.
Read-aloud text is clearly indicated and inserted in such a way as to not painfully stand-out. I'm a huge fan on how the new monsters have a paragraph of read-aloud descriptive text. There are a couple of handouts, nothing to write home about, but more than you usually get in an adventure. The PDF is password-protected, but the permissions are adequate for normal usage and they've bothered to bookmark this adventure.
The real strength of this adventure, the thing that would make me want to pick up more of these Dungeon Crawl Classics, is that everything is put together well. The story seems to have just enough meat on the bones to be useful, but doesn't present such an overwhelming carcass that you cannot strip what you need out for your game. The PDF is loaded down with ads or even any wasted space. The artwork is sparse, but not lacking, and does a good job breaking up the walls of text. I'll be able to tweak this easily for my own uses and likely get several good games sessions out of it.
I recommend you pick up Legend of the Ripper while you can!
*It is definitely a d20 adventure as it has all the OGL goodies at the end. I like how it was made as small and unobtrusive as possible. Much better than wasting a whole page or two on something nobody will actually read.