I don't want to deal with virtualenv for a local Python installation, I just want to install a few packages locally without dealing with the PYTHONPATH environment variable, how do I do that?
Python (as of 2.6 and 3.0) now searches in the ~/.local directory for local installs, which do not require administrative privileges to install, so you just need to point your installer to that directory.

If you have already downloaded the package foo and would like to install it manually, type:

cd path/to/foo
python setup.py install --user


If you are using easy_install and would like the package downloaded and installed:

easy_install --prefix=$HOME/.local/ foo


Update by RafiK

pip install --user foo


The following answer is provided for historical purposes:
It's a little more work if you are using pip to download and install:

pip install --install-option="--prefix=$HOME/.local" foo

