I just read this really interesting, theory on Mugglenet, but, even though it sounds way out there, we have to keep out minds open!

"This leads me to believe that the Half Blood Prince will most likely turn out to be someone who has not yet been intorduced to Harry Potter world. But what if the HBP is someone who hasn't even been born yet? What if he is the future child of what I believe to be the inevitable couple of Ron and Hermione."

Read it! It is very, very interesting! Read it here.