My favorite text editor for many years. No installation required: just unzip the files into the folder of your choice. Consumes very little disk space. Performs three tasks that are hard to find in one text editor: it saves files in Unix and Mac formats as well as Windows; it executes batch text files with one button click; and it opens urls in the default web browser with the user's choice of a single or double click. One feature it lacks is tabs: users must open multiple instances of the program to work on multiple files at the same time. It also does not have the capability to change case in bulk (e.g., ALL UPPER CASE, all lower case, Title Case, Sentence case).
A free, open-source text editor with an almost dizzying array of features. It comes with both unicode and ascii versions. A number of plug-ins are available to add even greater functionality. Notepad++ is far more robust than Win32Pad, but it takes much more time and effort to master its many nuances.
Jarte strikes a middle ground between the two programs discussed previously. It has more features than Win32Pad—most notably: tabs, spell checking, and case changes—and is much easier to use than Notepad++. And unlike either of those two programs, Jarte accommodates rich text format (.rtf) and Word documents (.doc), almost like Microsoft's WordPad on steroids. Jarte also presents a simple yet elegant appearance.
Tomahawk PDF+ is a decent enough text file editor whose distinct advantage is its ability to easily convert text documents into Portable Document Format (file extension .pdf).
Docx2Rtf is not literally a text editor. However, it does process certain text documents. Specifically, it reads Microsoft Vista Word 2007 documents (file type .docx) and allows users to save them as rich text files or convert them to .pdf files. This small program requires no installation: just unzip and use. Very convenient for users who only occasionally encounter .docx files but do not have Word 2007 or OpenOffice. [Both items added 8 September 2009]
TextCrawler - Find and Replace Text
This is another program that is not a full-fledged editor, but I included it in this section because its primary mission is to change the content of text files. TextCrawler allows users to search for and replace text within files. What distinguishes this program from other similar utilities is that TextCrawler incorporates the extremely powerful feature called regular expressions. In addition, you can even have the program create backups of each file before any text changes take place. Note: the user's manual indicates that TextCrawler does not work on file sizes above 500Mb(!). [Added 8 September 2009]