It's the sort of question that immediately provokes second-guessing, because one has to think carefully about the the impression one's books make. Will my Renaissance-era favorite authors make me look way too academic? If I show up with Anne Carson's Autobiography of Red, fond as I am of that book, will everyone assume I'm ripping off the idea from "The L Word"? And so on.
And there's the question of how familiar the books are, as well. If books are a common language, then bringing books nobody's heard of would be like trying to converse in Latin.* And bringing books everyone has a copy of would be like limiting the conversation to extremely well-worn catchphrases. I'm suddenly reminded of how LibraryThing calculates the relative obscurity of people's collections. (I feel another LibraryThing post coming on! Maybe later.) On the other hand, unfamiliar books are good for starting conversation, wouldn't you say?
So here's my provisional list: Labyrinths by Jorge Luis Borges; Shadow Train by John Ashbery; and Jonathan Strange & Mr Norrell by Susanna Clarke.** I tag anyone and everyone, but especially Bane, Cleis, the dynamic duo of About Last Night, and Clancy.
* Actually, I would date someone who could converse in Latin. Though I know from having tried it that forming complete Latin sentences on the fly is well-nigh impossible, so we would have to switch to English after exhausting our stock of dialogue from Latin for All Occasions.
** Is it cheating to post runners-up? Probably. But I also considered The Faber Book of Opera, A. S. Byatt's Possession, and Italo Calvino's Invisible Cities.