My son used to play this endlessly. I haven't, but I do remember hearing about a few of the things you all have listed.

Borrowing from an Alfred Hitchcock story, with a bit of an adaptation, you could have the trap be a room lined with steel, which gets hotter and hotter, eventually roasting the hapless warriors or what have you for an Ogres' Bar-be-Que!

No one has mentioned quicksand...another useful trap of sorts.

Sounds like fun!

kat