I have a really weird theory - I think TOM RIDDLE is the one mentioned in the prophecy.....just a thought, i mean the line 'neither can live while the other survives' doesn't seem to fit harry, seeing as though Voldie's alive and harry seems to be surviving alright...i'd need the whole prophecy in front of me, but i've been thinking about it for a while, and it seems to fit...apart from the 'born as the seventh month dies' bit
it would be just like JKR to put something like that in, and we've always 'known' that Voldie would be killed by love, maybe Tom is voldie's spark of humanity and comes out at the very end (a bit likie at the end of Phantom of the Opera)
Anyway, that's getting off the point...including the ring, the diary, the locket, the cup, nagini, Ravenclaw's something, Gryffindor's something, and Voldie himself (considering 7 soul fragments) that makes 8....but seeing as though there is no mention of nagini before the 4th book, it could be assumed that nagini was made into a horcrux after the diary was destroyed. He would have found out about its desruction from Malfoy, no doubt