Text editors are really important, especially on Linux where chances are you're going to be editing text sooner than later. For a programmer, or a sysadmin, it's one of the most fundamental and important tools that one uses on a daily basis.
For beginners, I recommend gedit, the editor that GNOME comes with, or kate if you're using KDE. They are feature-complete in terms of accommodating the beginning to intermediate user and their projects. There are also good supportive packages available to extend gedit to serve as a Latex editor, and to provide some more plugins, almost all incredibly useful.
So what's your favorite editor? And what are you using it for? Do you use different editors for different purposes?
Whatever editor you choose to use, do yourself a favor and use one that at least supports syntax highlighting. It will make your life - whatever you do with it - much easier. Good syntax highlighting also supports configuration files, not only programming source code, so those long config files you tend to get lost in are a thing of the past.
I personally use GNU Emacs - for pretty much anything except quickly editing a file using the GNOME desktop (there I just use gedit).
I use Emacs* as editor for
This is definitively not to start a flame war, I know vi(m) too and I use it sometimes over the command line while logged in remotely - but only if I haven't installed emacs yet. :)
By extension, I like to use Conkeror, a browser based on the Mozilla rendering engine, but pre-programmed with the Emacs shortcuts. And, I enabled the Emacs shortcuts on my GNOME desktop using this command:
gconftool-2 --set /desktop/gnome/interface/gtk_key_theme Emacs --type string
I found myself using nano as well,
Comes standard with debian distros, and many others and it has an easy to use menu when in the terminal so I dont have to "shift gears" and memorize much when using it. gedit and Kate I use in a gui. But find myself going back to terminal and using nano.