No Trick Treats
Here is a great idea to create a map of places that kids with dietary restrictions can visit when trick or treating.
The site lets treat givers add their addresses and the snacks they'll be giving out to a Google Map, and then it shows treat-getters the places in their area that have goodies that they can enjoy!
Ghostag is a crowd-sourced map of ghost sightings.
To tag a ghost on the map you simply need to click on a location and add the details of your sighting. If you manage to get a picture of the ghost (or failing that - the location of the sighting) you can also add that to the map.
The map uses the Google Maps API v3 Styled Maps function to create a suitably creepy look. When viewing the map turn on your speakers as it also contains some ghostly sounds and the occasional ghost like apparition appearing on top of the map.
As a special Halloween dispensation I'll include this crowdsourced map of zombie sightings, even though it uses the hauntingly popular OpenStreetMap.
The site uses the Ushahidi report mapping system to map the spread of zombies around the world.
Haunted Los Angeles Map
Creepy LA have produced this Google Map as a guide to reported supernatural activity throughout Los Angeles County.
Map of the Dead
This old zombie shooting game from Google is still good fun. The game-play is very simple - you have one minute to shoot as many zombies as you can. Although I might be mistaken, the game seems to be taking place at the University of Southern California so those might be students and not zombies. Sometimes it's hard to tell the difference.
This post would not have been possible without geoparadigm's spooky Halloween Bookmarks