41. "The Monkey's Paw" (1902) by W.W. Jacobs. This is the story Jacobs is remembered for, but as you've seen I've listed a number of his works, there is more to commend in his bibliography than just this one tale. That said, this is one of the all-time great short stories. I'm sure you already know (or think you know?) the story and its moral: be careful what you wish for.
42. "The Well" (1902) by W.W. Jacobs. Another fine story by Jacobs, this relates the falling out between two brothers, culminating in one's disappearance. When the beloved of the remaining brother loses a ring inside an old well, he suddenly becomes quite perturbed and determined to retrieve the ring alone. Why doesn't he want anyone else looking inside the well?
43. "The Adventure of the Second Stain" (1904) by Sir Arthur Conan Doyle. Another great Sherlock Holmes story, this involves the titular second stain - one stain lies on the rug, the other on the floor. Why was the rug moved after the murdered man died?
44. "The Adventure of the Six Napoleons" (1904) by Sir Arthur Conan Doyle. A great Holmes story where a man goes about smashing busts of Napoleon, seemingly insane. It takes Holmes to realize that there's more going on here.
45. "The Country of the Blind" (1904) by H.G. Wells. "In the country of the blind, the one-eyed man is king," so goes the proverb. In this wistful story, a mountain climber discovers the country of the blind, but finds that the proverb does not hold true. He soon discovers that his senses may be superior, but they mean less than nothing in a society which has made to do without.
"The Country of the Blind" can be found in The Country of the Blind and Other Selected Stories. You can read the text online here.
46. "Number 13" (1904) by M.R. James. A frightening James story which slowly builds up to one immensely effective moment. A guest in a hotel notices some odd occurrences. The room seems smaller during the night, larger during the day. At night, he sees a room next to him numbered "13." He can't find number 13 during the day. And someone is in that room.
47. "Oh, Whistle and I'll Come to You, My Lad" (1904) by M.R. James. Possibly James' finest story, certainly one of his best-known. Between his fun prose, James brings out a terrific ghost story about a man who digs up an unusual whistle, then blows into it. Unfortunately for him, something answers the call.
48. "The Treasure of Abbot Thomas" (1904) by M.R. James. This was my first exposure to James, it was in a filmstrip collection along with Amelia Edward's "Phantom Coach." A researcher solves the riddle of Abbot Thomas' supposed hidden treasure, but when he reaches in to take it...well, it's a moment that lived long in my imagination.
49. "A Tropical Horror" (1905) by William Hope Hodgson. A ship at sea is visited by a creature from the depths, something apparently prehistoric...something with little love for humans. Told in frantic passages as the narrator tries to conceal himself from the sea creature which tears through his fellow crewmen.
"A Tropical Horror" can be found in The Collected Fiction of William Hope Hodgson Volume 3. You can read the text online here.
50. "A Suspicious Gift" (1906) by Algernon Blackwood. Blackwood is best regarded for his supernatural tales, but this one manages to terrify without bringing in anything otherwordly. A man takes in a strange guest who has a gift of money for him. So what's the catch? And why does the guest walk so strangely?