I'm a long-time user of Wikipedia, and have a few little snippets of information to add here and there.
I have a wide variety of interests, and some have referred to me as a vast storehouse of useless information. Hopefully this will prove to be a useful trait here on Wikipedia. I would say I don't have any single overwhelming interest. As far as subject matter goes, I'm a bit of a generalist. I have a few major interests, but I wouldn't count myself as an authority on any one subject.
I would also just like to note that I think it's pathetic that my userbox is longer than my self-description.