Training without climbing

In 2 weeks, I'm heading out for a 3 month trip through Latin America. After that, I'll have 3 months to stay home and climb, and then I'm taking off for a 6 month AT thru hike.
The only bad part about these trips is that, while both places are home to some fantastic climbing, due to scheduling I won't be able to do any of it!
What are some basic exercises I can do to try and stay in climbing shape for when I get home? I won't have access to fancy workout equipment or weights, but I'm not adverse to using the world around me (trees for pull-ups, Etc.)

I'd say you have a good handle on it already. Stay active (to maintain endurance) and use whatever is at hand to maintain strength. Good luck and travel safely.
-Mackley
Added: I also do calf raises, with my toes on some sort of edge (such as a curb, stair, low rock feature etc.) as a way to maintain calf/foot/toe strength in times of little climbing.

crimp and hang from every doorway you walk through. religiously

Also do a YouTube search on "prison workouts". It sounds ghetto, but there's some great tips on, not only staying fit, but also getting stronger with limited resources.
-Mackley

buildering... or bouldering if you have access to some. grab a small finger trainer before you go. itll help pass time and also increse blood flow while hiking to higher elevations and help limited the sausage fingerness