Some popular short stories available online include "The Lottery" by Shirley Jackson and "The Cask of Amontillado" by Edgar Allan Poe. The Project Gutenberg website provides free electronic books and offers many other short stories online for free.
"The Lottery" by Shirley Jackson is a popular short story about a small town with a grisly tradition of stoning one unlucky resident per year. The townspeople gather on what seems to be an ordinary morning in the early summer. Children wander through the town, picking up stones and putting them in their pockets. Adults gather and discuss the event in a casual manner, as though it were just another local tradition.
During the lottery, a member of each family in town must choose a slip of paper from a box. The losing family must sacrifice one member. At the end of the story, the villagers stone Tessie Hutchinson to death.
"The Cask of Amontillado" is a tale of revenge by Edgar Allan Poe. The story takes place in an Italian castle during the late 19th century. The narrator explains that he must take revenge upon his former friend Fortunato because the other man severely hurt his pride. During a party, he gets Fortunato drunk and lures him into the dank basement of the castle by promising him that there is a fine cask of Amontillado wine in the cellar. There, he chains Fortunato into a tomb-like space in the catacombs and walls him in alive.