Okay, I wanted to get my thoughts down, so I'm writing this as I'm finishing reading everyone else's opinions.
Harry as a horcrux makes so much sense, but I never would have thought it up on my own. The only problem I see is that if Harry is a horcrux then it had to have been unintential because he intended to kill Harry, to use Harry's murder to create his last Horcrux.
The thing I really want to know though is what was the reason behind the gleam in Dumbledore's eyes at the end of Goblet of Fire when Harry told him that Voldemort had used his blood in the spell, and was therefore no longer vulnerable to Harry's touch? And how is that all going to be affected on July 30th (or is it 31st?) when Harry comes of age?
I had actually been rooting for Harry and Ginny to get together since Chamber of Secrets, only because I identified with the social backward young Ginny (not so much with the more-action-than-you-could-shake-a-stick-at Ginny). I think the reason Harry felt he had to distance himself from her is that
(1) He can intellectually accept the possibility of horrid things happening to Ron and Hermione, because he's not romantically involved with them. He wouldn't make stupid mistakes if they were in danger. With Ginny, the situation would probably be very different.
(2) He can conceivably distance himself from Ginny, since their close relationship is new, but not from Ron and Hermione.
But I still think that Ginny will be used against Harry. I'm interested to see if Ginny will object to being dropped in the last book, since she seemed pretty accepting of it. And it's not like Ginny will be unable to do anything useful to support Harry from the homefront.
As for the necklace horcrux being destroyed, where is the proof one way or the other? Nothing has been said that proves the horcrux was destroyed. RAB could easily have died before he figured out how to do it. I'd like it to be Regulus, but Ameilia Bones is also a good option. I don't think Rowling has come out and said whether or not we've been introduced to the character, so it could be someone completely new.
Lily/Snape theory: Snape in love with a Mudblood? I just don't see this happening.
Actually, I really don't agree that Snape is "good." Snape has never done a nice/good/benevolent thing in six books, except for the time he kept Harry from falling off his broom, in the first book, before anyone knows for sure if Voldemort is still alive. Snape committed cold-blooded murder.
Earlier in the book we're told that killing "rips the soul apart." I don't believe Dumbledore would have asked Snape to commit murder. Draco didn't have to kill Dumbledore to survive. Other methods to save Draco could have been attempted and should have been if Snape really is "good." People who are "good" don't kill defenseless, unarmed people just to save their own life.
I think Snape was using Legilmancy to learn what Harry was going to cast before he cast it, and he wasn't trying to teach Harry anything, just make himself feel superior by putting Harry down. I don't buy that he "saved" Harry by not killing him. It makes a lot of sense to me that Voldemort wouldn't want anyone else to kill Harry. If they did, they would have succeeded where Voldemort has repeated failed, making them a terrible threat to his power. Snape was following Voldemort's orders.
I'm interested to know what other people feel is good about Snape. You see the character of a man in the way he treats others. Look at the way he treats Neville. He acts exactly as he did in High School. There has been no progression in his character since he is first introduced.
I'm not saying that Snape is neccessary going to end book 7 evil. I would like to see Harry smush him into the ground. However, if he does end up good, I think it will be a change of heart that he has in book 7. I don't think he's good now.
