Well, I'm a student, so moving around isn't a real option right now. They
recently installed this lame window heat/AC unit which doesn't seem to work
very well. I leave it on 74 F but it seems to stay on all the time, which
seems to imply that it's not working so well or the room is losing heat
rapidly from somewhere. The floor is unusually cold for some reason, and I
haven't been able to figure out why. I guess I'll have to bother the
landlord, but I don't want them tearing up the room.
I sympathize with you. Besides putting up a plastic barrier on the
windows you don't use, try getting area rugs and space heaters from a
thrift store or Freecycle (I'm assuming you have bare floors if
they're cold).

I highly recommend checking out Freecycle for Baltimore. The goal of
FreecycleBaltimore is to reduce waste by connecting people who are
discarding goods with others who are seeking the same goods.
http://groups.yahoo.com/group/FreecycleBaltimore/

I've used Freecycle here near Seattle for all kinds of things. It's
amazing the high quality stuff people want to give away to make room
for new purchases.