Yesterday I visited the Lesbian Herstory Archives in Brooklyn, which is definitely a gem. Filled from floor-to-ceiling with books, papers, articles, videos, tapes, posters, pins, and clothing, it's pretty incredible.
Unlike most archives, they collect books as many come from small presses, are independently published, and/or go out of print so quickly.
I spotted many first editions or other intriguing copies of books by some of my favorite authors, including a 1937 edition of Djuna Barnes' Nightwood. (It was very hard resisting the impulse to pull out a big stack of books, park myself in a corner, and read away.)
Not sure I'll get to do any more bookish sightseeing for the rest of my trip -- I'm back in Boston tomorrow and do have to do some work today, le sigh. But this was a fun, surprising visit!