Here are some more additions to The Best Websites For Learning About Halloween:
Halloween 2009 is a neat resource from National Geographic (thanks to Interesting Pile for the tip)
Detroit Fights Devil’s Night is a TIME Magazine slideshow about a tragic tradition of arson in Detroit.
ESL Courses has good resources on Halloween and on The Day Of The Dead.
Happy Halloween Escape is an online video game that has potential as a language development activity, especially if it’s used with a walkthrough.