It's weird; at first I thought Ravenclaw because of my geeky thirst for knowledge; but then if Hermione can be a Gryffindor then it probably matters more what you want to do with the knowledge, which for my case is distinctly Gryffindorish goals like making it possible for disabled people to handle their own problems via technology, so that it will be harder for others to take advantage of them. And then on the other hand, Hufflepuff is pretty cool too, because it's about the only house that sees everybody as equally interesting and worth getting to know, and that appeals to my love of diversity; plus my tendency to simply never give up even if I'm scared or discouraged is Hufflepuff all the way. But if Neville can be in Gryffindor...
The only one I could never see myself joining is Slytherin. Ambitious schemers--whether they're wannabe Death Eaters or simply people who want to be famous and admired by others--just don't seem like me at all. I do occasionally catch myself thinking that I am superior to others, but I'm quite careful to keep that in check, especially since once you get to know other people you realize that you might be pretty cool, but so are they. And if Harry Potter can get out of Slytherin simply by not wanting to be in it, then that'd keep me out too.
So... ehh, it could be anything, really. I would probably be happiest in Hufflepuff, but it's entirely likely I'd end up in Gryffindor or Ravenclaw instead, partly because happiness isn't my top goal in life.
Think I overanalyzed that, really.