Oxford.  Chosen as the site of the Snape residence since I've read more books set in Oxford than Cambridge.  Said books being Laurie R. King's Mary Russell series and Dorothy L. Sayers' Gaudy Night, along with Dorothy L. Sayers: life of a courageous woman.

Certain aspects of the College of Aurors were also used in my fic "There Is No Such Place".  At one point, this was a sequel, before I came to my senses.

"Maybe I'm growing old."  "Or up."  From Mirror Dance by Lois McMaster Bujold.

Madam Dupont: named for one of the French teachers at Malory Towers.  Ah, Enid Blyton, without whom my life would be devoid of French stereotypes…

"If found, please return to Sauron, Lord of Darkness."  An alternative translation for the inscription on the One Ring, don't you know.  From an American video chain's advertisement for LotR.  Never let it be said that I don't draw my references from a wide variety of sources.

You are a little mystery to me. From "The Ship Song" by Nick Cave

Peach party dress. A reference to "Precious Things" by Tori Amos: "I remember, yes, in my peach party dress, no one dared, no one cared to tell me where the pretty girls are…" There's a Tori song for every fic, and a fic for every Tori song.

The Weasley jumper of interior decorating. I'm under orders from Beta Amy to mention that in America, that would be the Weasley sweater of interior decorating. So now you know.

Aurors made the best housebreakers. In the early Middle Ages, they'd been thugs and standover merchants as much as Dark Wizard catchers. La la Vor la la. Or at least, I think that's where I got it from, but I lent my copy of Barrayar to a friend, and I've yet to get it back… Where the hell is a thug or standover merchant when I need one?

"I'm an Unspeakable, not a miracle worker." I'm surely not the only one having a Robert Picardo moment.

I've been assured that a porch would be highly unusual in a British home like this one, but I'm simply not confident enough with the notion of a conservatory to, y'know, include one. In any case, there are a couple of important scenes taking place on that porch, and they would be markedly different if I changed the setting.

Rambaldi Institute: *cough*Alias*cough*RJ'sfault*cough*

Phillida Gride: I found the name Phillida in Justice Hall by Laurie R. King; 'gride' is an old-fashioned word meaning "to scrape with a sound that grates on the ears". Well, I was looking for a name that caressed the ear like nails on a blackboard…

Pluit: his name has something to do with rain. I lost the notebook where I keep these references, so you'll just have to take my word for it.

Evil ink: in tribute to Ashfae's "James Potter and the Year of Chasing", my very favourite James/Lily fic.

Thessaly: in the literature of ancient Greece and Rome, the witches of Thessaly were powerful and dangerous. They had the ability to draw down the moon, though no sources were clear on what this meant or how it was accomplished. Neil Gaiman's Sandman series features an interesting portrayal of one Thessalian witch, and depicts the drawing down of the moon in "A Game of You". Jocasta Kostakeidis is, of course, a Thessalian. (Her name comes from Oedipus Rex and that a Greek-Australian journalist.)

The three witches of Thessaly are also a Gaiman reference. Though having the Furies pursue Harry is a whole 'nuther plot bunny.

Vasily Radnov: His surname comes from the treacherous officer in Shards of Honour. See, I'm not just borrowing from Mirror Dance. Honest.

…something intricate involving thumbscrews, rusty safety-pins and ginger beer. Soft drink is also used as an instrument of torture in Terry Pratchett's Night Watch.

"Harry thinks he's a knight errant." Mirror Dance again. Written quite a few months before JKR and Hermione said, "Don't you think you've got a bit of a saving-people thing?"

"So if you know all that," said Lilith, "why are you out here, tempting fate and making me angry?" Echoes of Miles at the end of A Civil Campaign, though not intended as a deliberate reference.

I'm sure there was more, but I am slack and stopped taking notes. Feel free to come after me with an axe if you see something that needs attribution.