PoolAna is a Python library that helps you organize and run your analysis code. It principally supports an analysis style in which you write short, simple pieces of code that compute one thing for each event and store it in friend trees of the original input trees. When running the code, the input dataset is split up into a (sometimes large) number of sections of a certain number of events each, and then each section is submitted to a pool of worker processes.
I suggest using virtualenv and pip to install this in your home area:
~$ wget http://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.4.6.tar.gz
~$ tar xvzf virtualenv-1.4.6.tar.gz
~$ python virtualenv-1.4.6/virtualenv.py --distribute my-ana
~$ . my-ana/bin/activate # You must be in bash for this work properly!
~$ pip install PoolAna
Now build your analysis code inside the my-ana directory, and always activate the my-ana virtual environment to run it.