the key! the key!
what was the point of the key itself? was it just a metaphor?
good flick.
The key was also referred to in the painting with the three panels: utopia/eden, the garden (of lust and freedom) and hell.
I must say I wasn't very conclusive myself on what exact purpose the key had however I have the feeling that Martin's wife must have committed something 'wrong' (which is always a subjective term) which she didn't tell to her husband (maybe she had an affair). She then was punished (and perhaps someone sent her the key - which she held in her hand on one of those home clips) and sent to hell by the psychopath who committed suicide in his cell (or she was killed by Claire - which is another possibility).
More info on the painting "The Garden of Earthly Delights" can be found on Wikipedia.
So perhaps the key was the key to hell? I didn't pay much attention about the bible's statement at the begin of the movie so I might be also completely off. :)
Though I agree: great flick which I will someday watch again. :)
Greetings from Holland