Trying not to duplicate ER's and Tony's...

Books I own:

The entire Tolkein ouevre, read in internal chronological order, bouncing from book to book for the variations.

Always Coming Home - LeGuin

The Rediscovery of Man - complete collected short stories of Cordwainer Smith

Red/Blue/Green Mars - the KSR trilogy

The Coming of the King - retelling of the Arthurian saga through the POV of the weirdest Merlin I've ever encountered (and I've read 'em all), by Nikolai Tolstoy. Unfortunately, he abandoned the sequel(s).

Maus - Art Spiegelman. The streets are not paved with cheese.

PrairyErth - William Least Heat Moon (runner-up: Blue Highways). Last month I finally got to go to Cottonwood Falls, Kansas, and the old Z-Bar Ranch, which is now the Tallgrass Prairie National Preserve.

The Second Creation - a history of 20th C. physics, by Robert Crease and Charles Mann

Lonely Hearts of the Cosmos - a history of 20th C. astronomy, with emphasis on the value of the Hubble constant and the standard candle problem, by Dennis Overbye (one of Phil's favorites, too, i.i.r.c.)

The Discoverers - a history of science and changing worldviews, by Daniel Boorstin

Books I've borrowed (library) and want to own:

John Adams - the 2-volume biography by Paige Smith

American Sphinx (Jefferson), Passionate Sage (Adams), and The Founding Brothers (the whole Revolutionary cabal), all by Joseph Ellis.

The entire "Marcus Didius Falco" mystery series, by Lindsey Davies (I'm at least two books behind in my reading, I'm sure...)

His Dark Materials - the Philip Pullman trilogy

(and yes, of course, I also want to own a copy of "The Baroque Cycle")

Remembered fondly from much younger days:

Between Planets, The Star Beast, Tunnel in the Sky - Heinlein

The Borrower series - Norton

The Mushroom Planet series - Eleanor Cameron