postinstall sript from vagrant example box (having it somewhere web-accessible is easiest way to get it on to newly created VMs)

postinstall.sh

#!/usr/bin/env bash

# Apt-install various things necessary for Ruby, guest additions,
# etc., and remove optional things to trim down the machine.
apt_get_things()
{
  apt-get -y update
  apt-get -y remove apparmor
  apt-get -y install linux-headers-$(uname -r) build-essential
  apt-get -y install zlib1g zlib1g-dev libxml2 libxml2-dev libxslt-dev libssl-dev openssl libreadline5-dev
  apt-get clean
}

# Remove this file to avoid dhclient issues with networking
dhclient_things()
{
  rm -f /etc/udev/rules.d/70-persistent-net.rules
}

# Setup sudo to allow no-password sudo for "admin". Additionally,
# make "admin" an exempt group so that the PATH is inherited.
admin_secrets()
{
  cp /etc/sudoers /etc/sudoers.orig
  sed -i -e '/Defaults\s\+env_reset/a Defaults\texempt_group=admin' /etc/sudoers
  sed -i -e 's/%admin ALL=(ALL) ALL/%admin ALL=NOPASSWD:ALL/g' /etc/sudoers
}

# Install NFS client
nfs_common()
{
  apt-get -y install nfs-common
}

install_ruby_and_rubygems()
{
  # Install Ruby from source in /opt so that users of Vagrant
  # can install their own Rubies using packages or however.
  # We must install the 1.8.x series since Puppet doesn't support
  # Ruby 1.9 yet.
  wget http://ftp.ruby-lang.org/pub/ruby/ruby-1.8.7-p334.tar.gz
  tar xvzf ruby-1.8.7-p334.tar.gz
  cd ruby-1.8.7-p334
  ./configure --prefix=/opt/ruby
  make
  make install
  cd ..
  rm -rf ruby-1.8.7-p334*

  # Install RubyGems 1.7.2
  wget http://production.cf.rubygems.org/rubygems/rubygems-1.7.2.tgz
  tar xzf rubygems-1.7.2.tgz
  cd rubygems-1.7.2
  /opt/ruby/bin/ruby setup.rb
  cd ..
  rm -rf rubygems-1.7.2*

  # Add /opt/ruby/bin to the global path as the last resort so
  # Ruby, RubyGems, and Chef/Puppet are visible
  echo 'PATH=$PATH:/opt/ruby/bin/'> /etc/profile.d/vagrantruby.sh
}

# Install Chef & Puppet
install_chef_and_puppet()
{
  /opt/ruby/bin/gem install chef --no-ri --no-rdoc
  /opt/ruby/bin/gem install puppet --no-ri --no-rdoc
}

# Install insecure Vagrant SSH keys
install_insecure_vagrant_ssh_keys()
{
  mkdir /home/vagrant/.ssh
  chmod 700 /home/vagrant/.ssh
  cd /home/vagrant/.ssh
  wget --no-check-certificate 'http://github.com/mitchellh/vagrant/raw/master/keys/vagrant.pub' -O authorized_keys
  chown -R vagrant /home/vagrant/.ssh
}

# Install VirtualBox guest additions
install_vbox_guest_additions()
{
  VBOX_VERSION=$(cat /home/vagrant/.vbox_version)
  cd /tmp
  wget http://download.virtualbox.org/virtualbox/$VBOX_VERSION/VBoxGuestAdditions_$VBOX_VERSION.iso
  mount -o loop VBoxGuestAdditions_$VBOX_VERSION.iso /mnt
  sh /mnt/VBoxLinuxAdditions.run
  umount /mnt
  rm VBoxGuestAdditions_$VBOX_VERSION.iso
}

clean_apt_get_things()
{
  # Remove items used for building, since they aren't needed anymore
  apt-get -y remove linux-headers-$(uname -r) build-essential
  apt-get -y autoremove
}

vm_misc()
{
  # Zero free space to aid VM compression
  dd if=/dev/zero of=/EMPTY bs=1M
  rm -f /EMPTY

  # Removing leftover leases and persistent rules
  echo "cleaning up dhcp leases"
  rm /var/lib/dhcp3/*

  # Make sure Udev doesn't block our network
  # http://6.ptmc.org/?p=164
  echo "cleaning up udev rules"
  rm /etc/udev/rules.d/70-persistent-net.rules
  mkdir /etc/udev/rules.d/70-persistent-net.rules
  rm -rf /dev/.udev/
  rm /lib/udev/rules.d/75-persistent-net-generator.rules

  echo "Adding a 2 sec delay to the interface up, to make the dhclient happy"
  echo "pre-up sleep 2" >> /etc/network/interfaces
}

# Apt-install various things necessary for Ruby, guest additions,
# etc., and remove optional things to trim down the machine.
apt_get_things

# Remove this file to avoid dhclient issues with networking
dhclient_things

# Setup sudo to allow no-password sudo for "admin". Additionally,
# make "admin" an exempt group so that the PATH is inherited.
admin_secrets

# Install NFS client
nfs_common

# Install Ruby and Rubygems from sources.
# depends on: apt_get_things
install_ruby_and_rubygems

# Install Chef & Puppet (needs Rubygems)
# depends on: install_ruby_and_rubygems
install_chef_and_puppet

# Install insecure Vagrant SSH keys
install_insecure_vagrant_ssh_keys

# Install VirtualBox guest additions
# depends on: apt_get_things
install_vbox_guest_additions

# Zero free space to aid VM compression
# Removing leftover leases and persistent rules
# Make sure Udev doesn't block our network
# http://6.ptmc.org/?p=164
vm_misc

# Run if apt_get_things had run
clean_apt_get_things

exit

Why i did this? Because i want to select what i want install. This way, you can comment what you don`t want and be happy!