I totally thought about doing a murder mystery~ thing, but ran into trouble with logistics. I guess it depends on how casual we want it to be, because if it was run like a legit murder mystery "game" we'd have to have widespread participation and one person to know who the murderer was the run it, etc.
How were you thinking it could go?
All that said, I'm fine with anything else you've suggested and I'll also look around for simple Halloween~ memes.
On the subject of tags/threads, is there anything specific you want/need with any of mine that I can get put up?