I have several. I think there is real art to a well-crafted, meaningful title that roles pleasantly off the tongue and has just the right number of syllables. Good titles are really hard to come up with, and if they sound like poetry and make you feel feelings before you even know what the book is about (which is the basis for a lot of my favorites), well, that is an accomplishment indeed.
Here are some of my favorites, in no order, presented without explanation because more often than not there isn't one. Note that almost all of these are books I haven't read, and in many cases I don't even know what they are about. I feel like once I read a book, the title loses some of its mystery and beauty (especially if I don't like the book itself). I've italicized the ones I have read.
Good-Bye to All That, by Robert Graves
The Heart is a Lonely Hunter, by Carson McCullers
100 Years of Solitude, by Gabriel Garcia Marquez
Remains of the Day, by Kazuo Ishiguro
The Things They Carried, by Tim O'Brien
The Way Through Doors, by Jesse Ball
Portrait of the Artist as a Young Man, by James Joyce
The City & The City, by China Mieville (currently reading)
Man on the Threshold, short story by Jorge Luis Borges*
John Dies at the End, by David Wong
If on a winter's night a traveler, by Italo Calvino
Catch-22, by Joseph Heller
*if I had the time/inclination, I could list a ton of Borges titles, but I'll stick with just this one as it is my favorite (though not, interestingly, one of my favorite of his stories; I don't even remember what it's about!)