The History of Middle-Earth Index, by Christopher Tolkien. An index co-ordinating all the names in all twelve volumes of The History of Middle-Earth. As such a rather dry reference tome, but absolutely necessary for a Tolkienut.
The Chronicles of Chrestomanci Volume I: Charmed Life & The Lives of Christopher Chant; The Chronicles of Chrestomanci Volume II: The Magicians of Caprona & Witch Week; The Chronicles of Chrestomanci Volume III: Conrad's Fate & The Pinhoe Egg; Mixed Magics; by Diana Wynne Jones. All the books (so far) in her stories of the nine-lived enchanters called Chrestomanci. The Chronicles contain two books each, and Mixed Magics is a collection of four short stories.
Castle in the Air and House of Many Ways by Diana Wynne Jones. Sequels to Howl's Moving Castle.
The Unseen University Challenge: Terry Pratchett's Discworld Quizbook, by David Langford. Fiendishly nitpicking trivia challenges for smartypants who think they know all about it: it took me down a peg or three.
The Black Hole of Carcosa, by John Shirley. A little paperback that has intrigued me a long time because it contains Ivan Stang and J. R. "Bob" Dobbs as characters.
Lovecraft: A Look Behind The Cthulhu Mythos, by Lin Carter. A snapshot of the state of Lovecraftian studies as they appeared at the beginning of the 70's, by a great fanboy.
Videohound's Dragon Asian Action And Cult Films, by Bryan Thomas. Big thick brick of a book got for two bucks in HalfPrice's clearance section. All one needs to know on action films, anime, and big rubber monster movies from the inscrutable East, up to about 2002.
Into Hot Air: Mounting Mount Everest, by Chris Elliott. Another "novel" (as he puts it), this one mixes mountain climbing, celebrity causes, Yetis, Buddhist monks, and insane adventure into a heady brew of yucks. One of the few books that I actually laughed out to loud while reading.
Defining The World: The Extraordinary Story of Dr. Johnson's Dictionary, by Henry Hitchison. Another book on the perennially interesting topic (to me) of Dr. Johnson's world.
Dickens' Fur Coat and Charlotte's Unanswered Letters: The Rows and Romances of England's Great Victorian Novelists, by Daniel Pool. A sort of sequel to his What Jane Austen Ate and Charles Dickens Knew.
The Firelings, by Carol Kendall. The third in her Minnipin books, a sort of prequel, I guess, but it's kind of hard to tell, because the world seems so different. Unless someone had told me it was part of the series, I wouldn't have known.
The Stones of Green Knowe, by L. M. Boston. The last in her Green Knowe books, this is the one that explains how the old house actually comes to be built, and the magic that infuses it.
Four Freedoms, by John Crowley. His latest novel, totally non-fantastic, telling about life in WWII-era America in a plane building complex and the company town that supplies it.
The Ebb Tide, by James P. Blaylock. The latest of his Langdon St. Ives books. It's more of a longish short story, but it includes good illustrations by J. K. Potter, and the introduction of a winning new character, young Finn. In an afterword, Blaylock introduces the conceit that he is merely publishing the St. Ives book from manuscripts he found in a garden shed in England.
Wizardry And Wild Romance, by Michael Moorcock. "A Study Of Epic Fantasy." Moorcock's opinions on the genre he made his name in and now seems to mostly despise. Famous for the chapter "Epic Pooh," on why he thinks Tolkien's work to be pernicious to True Art.
El Borak and Other Desert Adventures, by Robert E. Howard. Pretty much what it says it is.
One Half of Robertson Davies; The Enthusiasms of Robertson Davies; A Voice From The Attic; and Discoveries: Early Letters 1938-1975, by Robertson Davies.
Curious Myths of the Middle Ages, by Sabine Baring-Gould. Published in 1894, and since used as a mine for ideas by authors from James Branch Cabell to Tim Powers.