Ubuntu Guide is a valuable source of information on what packages you need to install after installing a base Ubuntu Gutsy system on a laptop.
So instead of manually doing lots of apt-gets based on the Ubuntu I just put all the relevant ones into a single bash script. This will get all the usual multimedia codecs, firefox plugins, and a lot of other stuff. Just chmod 700 postinstall after creating it in your favourite editor.
Then from a terminal type
./postinstall
to run it. If there is a software package that you don't want below, put a # at the start of the line to comment out.
Note: the medibuntu.org repository allows you to apt-get skype,googleearth,win32codecs and other packages that cannot be included in the Ubuntu repos for legal reasons. It is not supported by Canonical so use at your own risk.
#!/bin/bash
# postinstall script
#!//bin/bash
#this should be all on one line
sudo wget http://www.medibuntu.org/sources.list.d/gutsy.list -O etc/apt/sources.list.d/medibuntu.list
#this should be all on one line
wget -q http://packages.medibuntu.org/medibuntu-key.gpg -O- | sudo apt-key add -
#update your packages database
sudo apt-get update
sudo apt-get install w32codecs libdvdcss2
sudo apt-get install mozilla-mplayer
sudo apt-get install flashplugin-nonfree
sudo apt-get install sun-java6-plugin
sudo apt-get install mozilla-plugin-vlc
sudo apt-get install kaffeine-mozilla
# astronomy programs
sudo apt-get install kstars
sudo apt-get install celestia
# genealogy
sudo apt-get install gramps
# plugin that allows you to type
#"apt:packagename" in the Firefox url bar
sudo apt-get install apturl
# bluetooth
sudo apt-get install gnome-vfs-obexftp
sudo apt-get install googleearth
# rar compressor/decompressor
sudo apt-get install rar unrar
# sticky notes
sudo apt-get install tomboy
#desktop system monitor
sudo apt-get install gkrellm
# allows you to tweak compiz
sudo apt-get install compizconfig-settings-manager
# lots of ubuntu tweaks in a handy GUI application
wget http://ubuntu-tweak.googlecode.com/files/ubuntu-tweak_0.2.0-1_i386.deb
sudo dpkg -i ubuntu-tweak_0.2.0-1_i386.deb
# music player/manager
sudo apt-get install amarok
sudo apt-get install sox
sudo apt-get install lmms
# sound editor
sudo apt-get install audacity
# codecs
sudo apt-get install mencoder avidemux transcode
sudo apt-get install ffmpeg2theora
# video player
sudo apt-get install mplayer
# mysql database server and client
sudo apt-get install mysql-server-5.0
# ssh server so that you can ssh login via terminal to your laptop from another box
sudo apt-get install ssh
# php web development language
sudo apt-get install php5
sudo apt-get install php5-cli
sudo apt-get install php5-gd
sudo apt-get install php5-curl
sudo apt-get install php5-mysql
# more bluetooth stuff
sudo apt-get install bluetooth gnome-bluetooth
sudo apt-get install bluez-gnome bluez-utils
# listen to thousands of internet radio stations
# and be able to rip the streams to mp3 format
sudo apt-get install streamripper
sudo apt-get install streamtuner
sudo apt-get install xmms
sudo apt-get install skype
# more codecs
sudo apt-get install non-free-codecs
# lightweight spreadsheet alternative to OpenOffice
sudo apt-get install gnumeric
# loads MUCH faster than Open Office Writer
sudo apt-get install abiword
# top notch programming editor
sudo apt-get install kate
# KDE office suite
sudo apt-get install koffice
# KDE browser and filemanager
sudo apt-get install konqueror
# allows SoundJuicer to rip to mp3.
sudo apt-get install gstreamer0.10-plugins-ugly-multiverse