As an update:

I installed and tested both JDarkRoom and PyRoom. They are both easy to use,
although light on features (this could be a blessing or curse, depending on how
you look at it).

Both of them are full-screen editors, IE: they both maximize on the desktop upon
startup. The default setup for both is a black background with green text. I
found this very easy on the eyes (reminded me of my old "DOS" days, and my green
screen monochrome monitor ;) ). If all you are looking for is a simple text
editor for writing, either of these will work well.

Another option, not on the list I sent earlier, is FocusWriter. It is a simple
text editor for writers as well, although it does allow you to set background
images. Depending on how you feel about this, it could be a liability.
Thankfully, you can also go to "black background green text" mode. It does seem
to have a lot of preferences options. FocusWriter is not in the normal Ubuntu
Archives. You can find it here:

http://gottcode.org/focuswriter/

And there is a nice article on it, which gives you instructions on installing
it, here:

http://lwn.net/Articles/413495/

Good luc