Following vaguely along with
a_chapter_a_day, I read not only the entry but the comment discussion of Chapter 13 in the first book. A couple of points:
"He glided toward them and landed noiselessly in a towering beech tree." -- Ninja!Harry. Despite being small and rather geeky, our boy is actually extremely physically adept. -
cadesma
Also, there was the very interesting business of Nicholas and Perenella Flamel's ages pointed out.
Mr. Flamel, who celebrated his six hundred and sixty-fifth birthday last year, enjoys a quiet life in Devon with his wife, Perenelle (six-hundred and fifty-eight).
So Nicholas was 665 and Perenella was 658 last year.
(Some have suggested the book was self-updating, but I don't think it matters. This isn't a big deal to the books or the plot (not yet, anyway) - we are given the numbers 665 and 658 "last year.")
So when the Sorceror's Stone was destroyed, and maybe when Nicholas died, he was 666.
Seven years later, when Harry's in his last year of Hogwarts, his wife would be 666.
What are the odds of Ms. Rowling choosing those numbers randomly?