I'm with Mahler on this one. Lots of good suggestions from the others as well, but resistance bands or a cable "gym" will allow you to most closely mimic or simulate your current routine (assuming you're doing a free weight program of big basics). Sounds like you don't want to deviate too much from what you're doing now if you can help it.
When I travelled through Europe for a month, I took this
http://www.lifelineusa.com/images/po..._gym_large.jpg with me and didn't skip a beat. It can be used for bar, dumbbell, and cable pulley type movements. (the bar breaks down to two pieces and the whole kit fit easily in my rucksack)