HippoEDIT!

Notepad++ is a free source code editor and Notepad replacement that supports several languages.

Sublime Text is a sophisticated text editor for code, html and prose - any kind of text file. You'll love the slick user interface and extraordinary features.

GNU nano is a small and friendly text editor. Besides basic text editing, nano offers many extra features like an interactive search and replace, go to line and column number, auto-indentation, feature toggles, internationalization support, and filename tab completion.

GNU Emacs is an extensible, customizable text editor—and more. At its core is an interpreter for Emacs Lisp, a dialect of the Lisp programming language with extensions to support text editing. The features of GNU Emacs include:

Text editor for the KDE desktop environment with support for multiple languages and syntax highlighting. It is extensible with plugins. Features a MDI interface.

Komodo Edit is a fast, smart, free and open-source code editor. Switching your trusty code editor is hard, but give Komodo Edit (or its big brother Komodo IDE) a try: it'll be worth your while.

PSPad is a freeware programmers editor in 8 languages for Microsoft Windows operating systems. Some features are highlighted syntax, ftp, projects and so on. Code explorer for Pascal, C/C++, INI, HTML, XML, PHP and more in development, internal web browser with APACHE support. Installation contains templates for HTML, PHP, Pascal, JScript, VBScript, MySQL, MS-Dos, Perl.

SciTE is a SCIntilla based Text Editor. Originally built to demonstrate Scintilla, it has grown to be a generally useful editor with facilities for building and running programs. It is best used for jobs with simple configurations - I use it for building test and demonstration programs as well as SciTE and Scintilla, themselves.