Harry Potter fans are trying to force J.K. Rowlings into continuing on with the series. I'm sorry folks but I don't think this one can be forced, even Rowlings herself cried when she finished the last book.
In the meantime there is a fan site creating a petition for this cause. Here is a link to the article 'Keep the Harry Potter books coming' - fans petition JK Rowling
"We, the undersigned, petition JK Rowling to write more new adventures for Harry Potter and his friends no matter what happens at the end of 'Harry Potter and the Deathly Hallows'."
To all those fans, good luck.