Here's how one woman lives in 90 square feet (and a block away from Central Park). It's an interesting space. I could see living (and, as she does, working) in that space, but I wouldn't choose to arrange it like that.
Have you ever seen this book: "Tokyo: A Certain Style"? It shows people living in even smaller spaces, with lots of good ideas about how to do it. It's fascinating to see how different people edit their possession to live in a tight space. Do you accept clutter or do you organize the hell out of it? Do you cut back on things to reclaim more empty space? What little luxuries and decorative items get in?