i dunno. I mean there are lots of possibilities - Harry's kids (probably Al) at Hogwarts and what goes on there, what harry does after the battle of hogwarts and how he gets to the place he is in his life at the train station, or a sequel like that, or you could do a like "meanwhile" like the year at hogwarts when harry and the trio are on the run, or their time at hogwarts told by someone who viewed it but not them, or you could do a prequel like harry before hogwarts, or told from someone else's point of view (so like when they were at hogwarts - could be anyone. Dumbledore, Snape (which would be interesting because it could be about James, Sirius, Lupin, Pettigrew Lily and Snape's time at Hogwarts), maybe Tom Riddle (that would be VERY interesting. Or someone we know less about, or even a character that wasn't in the books). So you see their are lots of possibilities, and unless you narrowed it down then i could prefer any of the types.

I´d like to read what happened right after 7th book. I´m really interested in Ron and Hermione´s life after that.

The Harry Potter books aren't written in Harry's point of view, so I don't think there would be one from someone else's point of view. The whole series was built up toward the final battle in which Voldemort was killed, so I don't think there's much left for a book set after that. I do think a prequel would be interesting. Then we could see what it was like when Voldemort was in power the first time and have James, or maybe Lily or Sirius, be the main character.

Hmmm....I think they're should be a Prequel either about Tom Riddle and everything that happened up to the night of Killing James and Lilly OR A big back story about Lilly and Severus' Realtionship and their years at Hogwarts. Severus && Tom <33

i love reading bout characters' past or their parents' adventures!!

well they are about harry, which was what i meant :P hence "harry potter..."
i think the most interesting story would be what aleapetrelli said. tom Riddle before killing James and Lily. That would be the most action packed, interesting book, because there is a lot of story line there.

i really don't see how a sequel would work...so i'm going to go with the prequel

next generation - Rose/Scorpius :)

lol Rose/Scorpius is awesome ;)

JK said no more books! But i want to know how was James & Lily's times in Hogwarts or what did happen between the 19 years mentioned in 7th book

Anything but a sequel. Talk about cheesy, there arent any major threats anymore.

a prequal would show about the lives of some of the characters before harry where as a sequal would be pointless, no major villan, lots of awsome characters gone, and reading about Harry in his adulthood would be akward for me.