Ever get tired of your word processor with it’s gazillion menus and buttons, overlapping windows and clutter? Try WriteRoom, an application that lets you write in full screen mode, green text on a black screen, the way computers were meant to be. 🙂 Just you and the text and a cursor. Nothing else.
In all seriousness, you get rid of all distractions, and you can just write. If you are a Windows user, try Darkroom (although I haven’t tried it).