harry potter and the previously mentioned locket
Ooh, I think one of my theories just got a little backing from JKRowling. Here's the new adult version cover for the 7th Harry Potter book, featuring a locket. Hmmm.
I have three theories on what will happen in the third book. The first two I've had since I read the 6th book, the third is more recent.
1. In book 5, when they were clearing out the Black house, they found many kinds of items. One was simply described as "a locket they couldn't open". Now Kreacher was quietly pilfering items from the house so they wouldn't be destroyed or gotten rid of. I think that locket is going to turn out to be the last horcrux. In fact, beyond that, I think this is going to play out into a similiar scenario as the one created by Tolkien in Lord of the Rings, where it is Frodo's mercy towards Gollum that brings success to the mission in the end. Gollum's leap into the fiery pit couldn't have happened if Frodo had not spared his life. That previous act of kindness saved Frodo from destruction when he was unable to save himself (being now fully under the spell of the ring). Now I don't think Harry is going to be under any spell, but I do think that the ties to Kreacher that he chose not to sever are going to become important in what happens in regards to finding that locket and in Harry gaining possession of it.
2. I think Snape is good and loyal to Dumbledore. I think that it will eventually be revealed that Snape told Dumbledore about the unbreakable promise and that Dumbledore asked him to, if the time came, be the one to kill him, because he believes that Draco can be saved from becoming like his mother and father.
3. I think Snape is going to be one of the characters that dies, and I think that his death will occur either just after we discover the truth about him, or as a result of him saving Harry. I agree with the people who have speculated that Severus was in love with Lily Potter and that even though he hates Harry for looking so like his father, he feels compelled to save him because Harry has Lily's eyes.
Any of you Potter fans out there have any theories of your own to share? It won't be very long until we can find out whether we guessed right or not. ^_^