I’ve found myself doing this 3 times in the last month. I thought I would write up what I do so that I don’t have to try to remember the next time I need to do this (which probably won’t be all that soon).

First, I do a basic install from the live CD.

Then I open Gnome-Terminal and do:
sudo apt-get install rxvt-unicode thunderbird git python-virtualenv build-essential emacs23

Then I install Chrome from the web.

That takes care of basic software installs. What remains is what I consider to be the essential customization.

First, move the Workplace switcher and Window list to top panel. Second, delete the bottom panel.

Add Gnome-Terminal, Thunderbird, and Chrome to the panel (select them in the Applications menu, right-click, and select “Add this launcher to panel”. Use the preferences (right-click on the terminal icon on the panel) for gnome-terminal to change the launch command it to rxvt -rv -sl 2000. Remove Firefox from the panel.

Finally, use the Keyboard system preference (Layouts tab, Options button, Ctrl Key position submenu) to make CapsLock a second control key. Then use the Windows system preference to select windows when the mouse moves over them.