(Semi-spoiler alert. I've read up to page 553. If you haven't, read on AYOR.) I'm told that from this point on, I won't be able to put the book down. I'll plan to be up late tonight.
So what's in the snitch? Obviously it will be something important. I had been thinking it's the ring, but I'm not so sure. On the one hand, if the Resurrection Stone is still functional (even though the horcrux aspect of it was destroyed), that would be a handy plot device to bring Dumbledore back, as he's got some 'splaining to do. But my gut feeling is that the Stone was destroyed. I don't think the Deathly Hallows were meant to be united. So the Snitch's contents will be some other surprise.
A colleague asked me a question I hadn't thought about before: do I think that Voldemort gets killed in the end? Now that I think about it, no, I don't. Rowling's magical world has always had too much realism in it for that: good people die, people are morally ambiguous at times, and life isn't always fair. So my hunch is that Voldemort is largely vanquished for now, but not completely killed. Perhaps the current Voldemort incarnation is killed, but the Nagini horcrux escapes, leaving open a future return. Evil is never completely overcome, and I think Rowling would have it that way in her world.
So, on to the home stretch...