Gender-less book

Is there any books that use 'they', 'them' and 'theirs' instead of 'he', 'she', 'him', 'her', 'his' and 'hers'?

I wanna see what genders people happen to assign the characters.

Argh... I can't remember the book, but it was all written in first-person, and you can't tell until the very end what sex the character was.  'I', 'me', and 'my' don't have genders.

There's also Left Hand of Darkness by LeGuinn.  That's about sex changes, sort of.  I didn't like it, though.