I'm assuming you already have a place and that you've been living there and your old roomie has moved out. If not, I think this information would still be helpful anyway, you just might have to alter it to your situation.

1. I would ask trusted friends. If they won't be your roommate, maybe they know someone who needs one. Any good friend would tell you the truth about someone else that they know.

 2. Facebook, Myspace, school bulletin boards (online and off). I'm sure there's a local network for your school in Facebook, and that seems like the fastest and most painless way to let people know you need a roommate. You'd also get the added bonus of being able to "screen" potential roommates before having to meet them.

3. If you're in university housing, you should go talk to them and see what options you have. Most likely, they won't kick you out because of a roommate issue, but they will probably assign you a roommate. It might not be a person you care for, but it would be better than absolutely having to find someone if you otherwise couldn't pay your lease.

4. If you're not in university housing, but your university has tenant services/housing services to help with students who live off campus and any issues they might have. Go see them now. That's their job--you won't be any worse off if you talk to them.

5. If you're in an apartment--try and find somewhere else to move and try to sublease your apartment. I know--you only have a week. But if there's a crazy student housing rush--and I imagine there might be because of your situation--I think you'd have a decent chance of finding someone willing to rent your apartment so you can find a smaller place. Only thing is to make sure that you have a place to stay before that person moves in. Click here  for some good information about subletting a place.

Also, if you google sublease agreement site:.edu , you'll come up with a lot of pre-created sublease agreements  that you could look at.

5. If you can't find anyone any other way and you still need a roommate, there's this kind of scary way. There's always Craigslist and your local alternative weekly. There's an article here about precautions to take for your basic safety with that kind of thing, with tips such as looking them up on Google and Facebook:.
I also definitely would talk to and meet the person (in a public location). Go over your dealbreakers. If you can't have pets in the place, don't even bother talking to the cat lady.

6. If you're in some kind of housing complex--the school's or an apartment building--see if you can downsize to a one bedroom. Yes, one bedrooms cost more per person than two, but one person paying for a two bedroom would cost more. Times are hard; your complex would probably rather take your money for a smaller space than risk losing money by putting your apartment up for rent (who knows if the next tenant could be a pyro?).

Good luck!