This to me is a very sad moment to depict--possibly the lowest point of the trilogy and the time in the plot where evil is most triumphant. Our hero has finally given in to the lure of the ring, and the seduction and temptation it represents have finally prevailed over the "fool's hope" that a little hobbit could summon the will to destroy it. Rather than a climactic struggle between good and evil, we have here a struggle between two sadly fallen creatures who are both overcome by the power of the ring and are lashing out violently in an attempt to possess it. It is a kind of celebration of everything that Sauron stood for.
Ironically, in the end good was unable to triumph over evil--evil ultimately destroyed itself by sheer accident. This moment represents everything tragic about the Lord of the Rings saga. Gandalf prophetically stated in film one that, "There is only one Lord of the Rings, and he does not share power." That selfish greed and debilitating lust for power are what this moment represents for me--the point where Frodo says, like Gollum before him, "The ring is mine!" and in so doing, becomes the very evil he set out to destroy. It was a shocking and painful statement to read in the book, and although altered somewhat by PJ, the film still portrays the failure of Frodo as he succumbs to corruption. Having an angry and violent Frodo abandoning his sense of pity and hope of redemption and striking out against Gollum to reclaim the ring sums up all of this high drama quite nicely.
The question remains--is that how I want Frodo immortalized in my collection?