Slim down a Raspbian NOOBS install, but leave omxplayer. ( based on https://blog.samat.org/2015/02/05/slimming-an-existing-raspbian-install/ )

Slim-Raspbian.sh

#!/bin/bash

# GUI-related packages
pkgs="
xserver-xorg-video-fbdev
xserver-xorg xinit
gstreamer1.0-x gstreamer1.0-omx gstreamer1.0-plugins-base
gstreamer1.0-plugins-good gstreamer1.0-plugins-bad gstreamer1.0-alsa
gstreamer1.0-libav
epiphany-browser
lxde lxtask menu-xdg gksu
xserver-xorg-video-fbturbo
xpdf gtk2-engines alsa-utils
netsurf-gtk zenity
desktop-base lxpolkit
weston
pi-greeter
bluej leafpad
claws-mail
raspberrypi-artwork
lightdm gnome-themes-standard-data gnome-icon-theme
qt50-snapshot qt50-quick-particle-examples
gconf2 gconf2-common gconf-service
gnome-menus 
libreoffice
lxde-core lxappearance lxde-common lxsession pcmanfm
openbox
"

# Edu-related packages
pkgs="$pkgs
idle python3-pygame python-pygame python-tk
idle3 python3-tk
python3-rpi.gpio
python-serial python3-serial
python-picamera python3-picamera
python3-pygame python-pygame python-tk
python3-tk
debian-reference-en dillo x2x
scratch nuscratch
timidity
smartsim penguinspuzzle
pistore
sonic-pi
python3-numpy
python3-pifacecommon python3-pifacedigitalio python3-pifacedigital-scratch-handler python-pifacecommon python-pifacedigitalio
oracle-java8-jdk
minecraft-pi python-minecraftpi
wolfram-engine
"
# Because of of https://github.com/RPi-Distro/raspberrypi-ui-mods/issues/2 (thanks @robertely)
apt-get -y remove raspberrypi-ui-mods

# Remove packages
for i in $pkgs; do
	echo $i
done | 	xargs apt-get -y remove --purge 

# Remove automatically installed dependency packages
apt-get -y autoremove

# Remove all packages marked rc (thanks @symm)
dpkg --list |grep "^rc" | cut -d " " -f 3 | xargs dpkg --purge