Vagrant

"Vagrant" is a system for managing virtual machines

http://vagrantup.com/

You set up a config file that sets up the vm, including installing packages and configuration settings.

As an example I am setting up a virtual machine to run Xastir under Parallels on my Mac.

cd Projects
mkdir xastir
vagrant init parallels/ubuntu-12.04
vagrant up --provider=parallels 

Downloading the Ubuntu ISO image takes 15 minutes on a reasonably fast connection When it's done you can connect with

vagrant ssh