Book 7

JK Rowling Tells: (all below is confirmed)
-One of the characters will become a Professor. It's not Hermione, Harry, or Ron; but JK Rowling hinted it might be Neville. (Maybe Neville could teach herbology?)
-We'll find out about the Potters' occupation and why they were so rich
-We will learn why some wizard come back as ghost and some don't. JK Rowling has told us that, "Happy people don't become ghosts."

Concerning Hogwarts:
-Harry will be Head Boy.
-Hermione will be Head Girl (duh!)
-Hogwarts is closed for a "temporary" basis.
-Hogwarts stays open, but few students return. The dormitory rooms are shared by two years now.

Outside Hogwarts — Home, Family, Friends and Enemies:
-Something big will be revealed about Lily Potter's career.
-We'll find out why it's important that Harry has his mother's eyes.
-Mr. Weasley's flying car will return.
-Someone/thing kills the Dursley's.
-Lupin will be killed by Wormtail. [It is possible, since Wormtail now has a silver arm and silver kills werewolves.]

Magical Community In General:
-Harry finds out more about Azkaban (and gets a look at it).
-The Dementors terrorize Diagon Alley

Titles and Book Publishing:
-The last word of the book will be "scar" CONFIRMED
^{Note: This may change when JK Rowling edits the book.}

Misc.:
-Pettigrew returns.