I don't really like virtualenv because you have to activate it to do anything and deactivate it if you want to go to another project or work on something unrelated. I'd much rather it work by the project directory so I don't have to worry about the activation part (this is why Node's package manager, for all its issues, is great: you install in a local folder unless you explicitly supply the -g flag). At least I should be able to install packages to my home directory.