I just finished reading Harry Potter and the Half-Blood Prince, so I want to post while it's still fresh in my addled little head.
1. I don't think Dumbledore is truly dead. It's either some sort of ploy to fool Voldemort, or an Obi-Wan, if you strike me down I shall only become more powerful thing.
2. Dumbledore wasn't begging Snape for mercy, he was begging Snape to fulfill his obligation to 'kill' him.
3. Snape has not gone back to being a Death Eater. He is still working for Dumbledore. When Snape and Draco were escaping, and Harry kept trying to stop him, Snape seemed more annoyed than murderous. Snape could have easily done a lot more harm to Harry than he did, and seemed to be giving him advise even through his hatred of our hero.
4. Ginny will find a way back to Harry. She's a lot smarter, more patient, and wiser, than anyone gives her credit for. She has watched Harry and his 'hero complex' for quite some time now, and obviously expected his selfless pushing her away. What Harry doesn't realize is that in the eyes of the enemy she's already linked to him, and thus a valid target. Plus she can take care of herself better than most of them. She is also the only other one with a link to Voldemort, so she's not exactly out of harm's way no matter her romantic entanglements.
5. I am an incredibly geek. Not the biggest one, but certainly in the top 20th or 30th percentile. ;-)
I thought this was the best book of the series. I know that puts me in the minority, but the reasons I liked it seem to be the same reasons many didn't. There was much less exposition, and much more story in this one. It almost seems like Rowling has grown as weary of writing every single class and discussion as I have of reading them. I re-read Order of the Phoenix before Half-Blood Prince just to refresh my memory, and it took nearly two-thirds of that book for the story to really kick in. Half-Blood Prince, on the other hand, hit the ground running and never stopped. Admittedly she left a lot of loose ends, and the next book, if indeed if it is to be the last, has a lot of ground to cover. Rowling has already proven that traditional outcomes are not necessarily the way she'll go, so discussions of will Ron and Hermione get married, or will Harry and Ginny are rather moot. So far these characters have avoided the 2-dimensionality of many fictional people and acted more like real teenagers. I don't think we need worry about such classic, and in my opinion trite, wrap-ups as multiple marriages, and happily-ever-afters. I would like to see a father figure enter Harry's life without biting it at the end, but then who's to say if any of the main characters are safe? If Rowling will whack Dumbledore, are any of our heroes out of danger? Only the author knows, or maybe not. I have written short stories where the characters did, or said things that surprised me, but made sense. I think the greatest testament to Ms. Rowlings prowess is not her fame and fortune, Paris Hilton is rich and famous(and completely useless), but rather the fact that so many of us are totally hooked on her stories. What started as a book for young children has become a masterwork of people who don't exist, but we care about as if they did. I cried when James Doohan died, and felt strange for mourning someone I never met. Imagine my incredulity this morning when I teared up while reading about a funeral for someone who I not only never met, but who never existed in the first place. That is the highest praise I think any author can hope for.
Congratulations, Ms. Rowling, on a job well done.