1. Scary Maze Game: http://scary-mazegame.net/
NOT WORKING ANYMORE
You may be familiar with this one.
2. Ghost Photos: http://www.ghostresearch.org/
This society explores photographs that have unusual objects or figures in them, you can take a look at such pictures.
3. Creepy Pasta: http://www.creepypasta.com/
Of course you know about this. This site is full of terrifying stories by a variety of contributors.
4. Burning Room: http://www.jonaird.co.uk/burning/burning.html
This game takes you through an interactive experience in which you click on objects in the room to pick them up.
5. Interactive Blair Witch Experience: http://www.blairwitch.com/experience/360/
Use your flashlight to look for objects in this 360 interactive version of the Blair Witch Project.
6. Possession Begins: https://www.possessionbegins.com/
An interactive experience, if you close your eyes the posession will begin, you'll hear a voice, you can try to escape by opening your eyes but be prepared for what you'll see.
7. John Hancock Life Expectancy Calculator: https://www.johnhancockinsurance.com/life/life-expectancy-tool.aspx
Gives you a prediction of when you will die based on your age, BMI and activities.
8. Online Ouija Board: http://www.brainjar.com/dhtml/ouija/
Ask anything and then place your mouse on top of it to get an answer to your question.
9. House Creep: https://www.housecreep.com/
It's a site with information on the history of certain properties so you can see houses nearby where interesting things have happened like owners found dead, DEA raid, etc.
10. Scary Faces: http://nightmare.mit.edu/#services
Help the MIT algorithm for scary faces by picking the ones that you think are scary.
11. Pumpkin Carving: http://www.bloompetals.com/index.php?c=pumpkin
If you want something more relaxing, you can carve pumpkins online.