There are two main categories for these applications. Those that you can install from the System -> Administration -> Synaptic Package Manager, and those you can’t.

Synaptic Package Manager

• GIMP
• Inkscape
• FileZilla FTP Client
• Amarok
• Audacity
• Wine
• VLC
• PulseAudio Volume Control (pavucontrol)
• Vuze (w/ RSS Downloader Plugin)

(Then to get the best of studio I also install)

• ubuntustudio-audio-plugins
• ubuntustudio-video
• ubuntustudio-audio
• ubuntustudio-graphics
• ubuntustudio-controls

From Website

• Picasa – http://picasa.google.com/linux/
• Truecrypt – http://www.truecrypt.org/

More Complex

• Gnome Do (Look here for complete tutorial)
  In a terminal write (Cut and paste entire section):
  gpg --no-default-keyring --keyring /tmp/gnome-do.keyring --keyserver keyserver.ubuntu.com --recv A5D19FDCAA6ABB440CD3464628A8205077558DD0
gpg --no-default-keyring --keyring /tmp/gnome-do.keyring --export --armor A5D19FDCAA6ABB440CD3464628A8205077558DD0 | sudo apt-key add -
rm /tmp/gnome-do.keyring
sudo gedit /etc/apt/sources.list
  Add following lines to Sources List then save
  deb http://ppa.launchpad.net/do-core/ppa/ubuntu jaunty main
deb-src http://ppa.launchpad.net/do-core/ppa/ubuntu jaunty main
sudo aptitude update && sudo aptitude install gnome-do
  When you run Gnome-Do for the first time, I suggest you change to preferences to take advantage of the “Docky” theme, and add in what plugins you see fit.
• Ubuntu Tweak (Look here for complete tutorial)
  In a terminal write:
  sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com FE85409EEAB40ECCB65740816AF0E1940624A220
sudo gedit /etc/apt/sources.list
  Add following lines to Sources List then save
  deb http://ppa.launchpad.net/tualatrix/ubuntu jaunty main
deb-src http://ppa.launchpad.net/tualatrix/ubuntu jaunty main
sudo apt-get update
sudo apt-get install ubuntu-tweak