after the destruction of the two trees, yavanna explained that the reason she could not recreate them was that there were some deeds that can only be accomplished once, and that the creation of the two trees was one such deed. she could, however, sorta revive the trees, with the light of the silmarils, but then feanor denied, saying that the silmarils were another such deed that could only be created once, and that he would sooner die then see his greatest deed destroyed, even though it may have brought back life to yavanna's greatest deed.
so, my question is... what other deeds fell into this catagory? the rings of power are probably another such deed. as the faq i posted earlier about the rings of power suggests, this could be the reason why sauron didn't make ten rings for men, or eleven, or some number greator than nine. this would also probably be celebrimbor's greatest deed.
i believe another such deed could be when melkor managed to ellude even the gaze of the valar through the unlight of ungoliant, and with this, managed to pretty much deprive the world of two such deeds.
frodo's great deed would probably be his destruction of the one ring, gandolf's great deed would probably be the slaying of a balrog, or perhapes the returning to middle earth as gandolf the white, or something.
what do you think some of the other deeds are?