On Linux, I use the Bluefish editor bluefish.openoffice.nl . I use it because it was made for this. I don't use the toolbars, I don't use much stuff, but I got used to it I don't know how.
On Windows I resort to Notepad++ when I have to code. I will actually check those editors Kroc has shown, because they look promising. I think Notepad++ is too bloated, although it isn't. I don't know, it's a combination of something that stresses me in Notepad++. I do know changing the font to DejaVu Sans or Lucida Console 8pt helps reduce a little the bloat, but still not enough.