FocusWriter is a simple, distraction-free writing environment. It utilizes a hide-away interface that you access by moving your mouse to the edges of the screen, allowing the program to have a familiar look and feel to it while still getting out of the way so that you can immerse yourself in your work. It's available for Linux, Windows, and Mac OS X, and has been translated into many different languages.

Features:

TXT, basic RTF, and basic ODT file support
Timers and alarms
Daily goals
Fully customizable themes
Typewriter sound effects (optional)
Auto-save (optional)
Live statistics (optional)
Spell-checking (optional)
Multi-document support
Sessions
Portable mode (optional)
Translated into over 20 languages