chest:
pushups work great as mentioned above - feet raised higher than torso, level with torso, and lower than torso; bed presses, basically like floor presses with a bar, except lifting up the edge of a bed. put phone books or something underneath the corner posts to lift the bed enough to get under it, kinda like safety bars.
tris:
dips on a couple of tall chairs, counter tops, and tables - or do dips on chairs with feet propped up on a bed ; seated or standing tri extensions with a chair; wall presses; pushups with hands close to each other; lying tri extensions pushing up the edge of a bed if it's not too heavy.
bis:
alternating bi curls with chairs; alternating hammer curls with chairs; brace hand on a wall, lean forward a bit and do concentration curls with a chair; pick up the edge of a bed, lean forward a bit and curl it.
shoulders:
shoulder presses with chairs; lateral raises with chairs; bent over laterals with chairs; again assuming they aren't too heavy.
legs:
bodyweight squats for as many reps as you can; bodyweight lunges; wall squats if you can find a smooth surface; kneel on the floor, brace feet under something ( bed if it's heavy enough ) and lift yourself up using hamstrings only.
back:
buy one of those portable chin up bars that hook up on doorways; if there are any surfaces you can hang from which supports your weight do pull ups on that, either with feet hanging or propped up on an elevated surface.
can't think of much else offhand. if you have two matching suitcases with handles, fill em up with stuff and use those instead of chairs. i know a lot of these sound kind of out there, but they worked well enough for me in the past whenever I couldn't get to a gym.
