(Ha, it feels very strange being here again, after a reaaally long break. In a nice way, of course.)
Fordim Hedgethistle, I was very intirigued by your reflections on the themes of doom and judgement. I had never seen it quite like that, but now that you brought it up so eloquently, it seems very natural.
One could also argue further that from the moment on when Gandalf falls - when they have no leader anymore, and must truly begin to make choices - the real test begins for the two men of the Fellowship, and judgement will eventually be passed upon both of them too: the other will face his doom, the other be judged worthy of his heritage.
On to a compleately other matter:
The thing that struck me the most when I re-read the chapter for this discussion, was defininetly Tolkien's masterful use of none other than our beloved action-film clichès! Especially the first part of the chapter, with it's desperate defence battle before we get to the real climax on the bridge, is pure Indiana Jones. Indiana Jones with immensly more depth, complexity and poetry, but still the basic gimmicks and tricks to suprise, scare and rouse the rader/viewer are all there.
There is the little guy (here in more than one sense...
) who shows suprising strength and courage - Frodo's heroic attac - , the sudden turn of events when they thought they were in the clear - the orc-chieftain stabbing Frodo - and finally the hero who saves the day in a situation where all others fail - Aragorn conquering over the said orc.
All these things show that Tolkien's isn't an expert only in writing fictitious history and creating detailed legends. He can also etertain the reader with good action-writing, which is finally made clear to the reader in The Bridge of Khazad-dûm. The chapter is important in many ways, and the change in the storytelling of the whole book is certaily one of them.