Harry/Ginny = YES!!!
I was so happy.
I thought of Regulus Black, too. But if we all thought of him, would Rowling be so obvious?
I thought Draco had something up his sleeve, crying to Moaning Myrtle; I'm still not convinced he didn't. But I'm glad he didn't have the evil in him to actually kill Dumbledore.
The polyjuice potion theory is attractive, but it doesn't change your voice, does it? I haven't read that book in so long, I'm not positive. Harry would definitely notice if Dumbledore had Snape's voice.
I have to admit I'm still hoping that Snape doesn't turn out to be Voldemort's toady. In the scene where he makes the Vow, doesn't it seem like he's guarding his words very carefully, and trying to discover what Draco's task is? And there's the conversation between Snape and Draco, where Snape is saying, "If you tell me what you're doing, I can help you."
I can see Dumbledore sacrificing his life in order to defeat Voldemort. Plus, he trusted Snape despite all the evidence in the world against him. I'm remembering Dumbledore making Harry swear to keep giving him the potion, even if he had to pour it down his throat... even if it killed him. Could he have had similar agreement with Snape? ...that if it came down to it, Snape would kill him to save Harry, and/or to solidify Voldemort's trust of Snape so that he could find out V's secrets -- maybe, where the horcruxes are hidden? It did seem like Snape hesitated; Dumbledore's pleading with him at the final moment could be, "Do it, Severus, this is the only way..."
Maybe I am grasping at straws... I do want Snape to turn out to be on the side of good, in the end... if only so Dumbledore's trust in him will turn out to be justified.