I spend a lot of time editing text as I prepare for gaming sessions. Focuswriter is a great, theme-able text editor which allows you to do your RPG writing in a stylish way.
FocusWriter is a fullscreen, distraction-free word processor designed to immerse you as much as possible in your work. It runs on Windows, Mac or Linux. The program autosaves your progress, and reloads the last files you had open to make it easy to jump back in during your next writing session, and has many other features that make it such that only one thing matters: your writing. FocusWriter utilizes a hide-away interface: simply throw your mouse to the top, bottom, or right side of the screen to gain access to a number of customizable options and useful information, then flick it aside when you’re no longer interested.
Download FocusWriter here.