I was thinking yesterday about the various types of life lessons Harry learns throughout the books, and how he learns them. Romance, or romantic love, for example. He never really gets a lesson all at once, his understanding is slowly built up through lots of different incidents — some he's involved in, others where he's more of a passive observer. And as I was trying to trace out various principles and how he comes to learn about them, guess what image popped in my head? A map of the London Underground. Which may or may not mean anything, but I thought it was kind of cool.
Also read a bit on the Lexicon (under Dumbledore's profile) about the connections of Dumbledore's names to the Beowulf epic. Beowulf slays the monster Grendel, which sounds an awful lot like Grindelwald. He then dives into a lake and gets Grendel's mum, which reminded me of Harry's second task in GoF. The name "Beowulf" has been translated by some as "bee-wulf"; the "wulf" part might have something to do with the Wulfing clan that shows up in the poem, and sounds like one of Dumbledore's middle names, Wulfric. And "Dumbledore" was an Old English word for "bumblebee." I followed up on bee mythology a bit, and the most significant thing that turned up was the name Merope, which means bee-eater, and somehow refers to an important archetypal character in various bee mythologies. All of which may still amount to nothing in terms of shedding light on the mysteries of Harry Potter, but seemed worth noting down for future reference nonetheless.
Finally, I read the story of Parzival, the Grail Knight, last week. Dumbledore's middle name Percival supposedly refers to this guy, and I have to say I was really struck by how similar the powers of the Holy Grail are to the Philosopher's Stone. Eternal life and riches, basically. I suspect — and I think JKR would cautiously agree — that they were just two different names and mythologies for the same thing. That same thing that I think the Potter series has been leading up to as well.