rei-c's wincest story A Threefold Path to Redemption (http://rei-c.livejournal.com/952440.html) includes a crucifixion scene in hell (where Sam has to recreate the last steps of the Messiah). It's pretty screwed up stuff and the most disturbing fic I've read yet (but really intriguing and well-written if you can stomach it) - just be warned.