jEdit is a programmer's text editor written in Java. It uses the Swing toolkit for the GUI and can be configured as a rather powerful IDE through the use of its plugin architecture.
I love it because it is open-source, platform agnostic, very customizable, good looking and pleasant to use.
I use jEdit daily and have done so for years. It collects a number of features together under a single application and has a strong base editor. The features I use have changed over the years, but that's just a testament to its utility :)
Highly customizable. If you know Java, you can write your own macros and plugins.
Superb editor with a plethora of features. Thank you.
Oh PLEASE hire a UI designer!