Here is my opinion on what will happen to the characters after they leave Hogwarts. Since we don't think/know J.K. Rowling is continueing after book 7, we can think anything, right?
Harry Potter: I think either J.K. Rowling will either have Harry kill Voldemort in book 7 or have Harry killed. Since we hope Harry will live and kill Voldemort, I think that Harry will remain in very close touch with his closest Hogwarts friends. I think the Dursleys will kick him out and Harry will live alone for a while. I think he'll get married and/or teach at Hogwarts then become headmaster.
Ron Weasley: I think he'll work in the Ministry in the same department his father does. I definitely think he'll marry Hermione! He will remain in close touch with Harry and maybe teach at Hogwarts too.
Hermione Granger: I think she'll become a teacher at Hogwarts, definitely! I think that she will either marry Ron or be single forever. I also think she'll make some big organization in the ministry or make a huge magical discovery.
Neville Longbottom: Him? I think he'll either be a Healer at St. Mungo's or become Defense Against the Dark Arts teacher or Herbology. I have no clue why I think that but that's what I think.
Percy Weasley: Considering his additude in OotP, I think he'll die miserable! MUWHAHAHAA! The brat...
George and Fred Weasley: Their joke shop will become so huge they'll be filthy rich. They'll go down in history and give alot of money to help out their family.
Ginny Weasley: I think she'll become very best friend's with Hermione and become of the "gang" meaning she'll be a big part in their lives and probably be at a job with Hermione or Ron. I also now support the G/H ship.
I want her to marry Harry! Even though I still kind of support the C/H ship, I think I'm a little more towards the G/H ship now. But she will definitely do something BIG in quidditch.
Draco Malfoy: I think he'll marry Pansy Parkinson and become very rich then get a life sentence in Azkaban along with Pansy
Crabbe and Goyle: Have the same fate as Malfoy
Hagrid: I think that he'll be at Hogwarts teaching Care of Magical Creatures and then stop after he publishes a book all about magical creatures or something like that and become very rich but still help Dumbledore out alot.
Dumbledore: He'll live forever! Muwhahaha ^_^
Er, please let me reassess my thoughts on this. It's a very low priority on my to-do list to revamp this website, but I've got some pretty strong opinions.
Hey! Here's a thought! Go to: Inigo Imago