I would create a group on Facebook & invite all of your friends. You could keep the group open & encourage your friends to invite their friends as well.
...OR...you could post something on craigslist. But, please be careful & meet them in a public place to chat before inviting them into your place of residence where you want them to possibly move in. Even then, have a friend or boyfriend with you. These things can be scary! Or maybe I'm too careful? haha. Hope this helps, at least a bit. This is just how we have always found a sublease for a room or two in our home at college, when one of us has an internship or leaves for the summer.