Well I certianly want to so I'll just say so before hand, like this.
***SPOILERS***
Indeed, one thing most people don't know (because they are not anal enough to research the book as well) is that Eli is supposed to be completely androgynous, she states a few times in the movie that "she is not a girl", when in fact she is telling the truth, she isn't, in fact in the movie the "crotch shot" supposedly shows a castration scar, something I didn't notice but then maybe I just wasn't looking as intently as others. She is also supposed to be an almost complete opposite of Oskar, though this isn't show overly in the movie it is supposed to be a big part of the book.
Also interested movie trivia, Eli's voice is dubbed by an actress with a deeper voice because her actual voice is to high pitched.
I also really loved the scene near the end with Eli going into Oskars house uninvited, very disturbing.