virtualenv

virtualenv is a tool to create isolated Python environments. install it with:
easy_install virtualenv
The basic usage is:
$ python virtualenv.py ENV
Where ENV is the name of the environment that you want to create.
Or,
virtualenv --no-site-packages ENV
Creating the virtual evn this way will not inherit any packages from the site-packages folder. This can be used if you don't have control over site-packages and don't want to depend on the packages there, or you just want more isolation from the global system

Beautiful! :)