So I'm not much of a creative writer, but (obviously) I enjoy writing, and lots of times I want to write stories and such.
I really enjoy Final Draft for that reason. It's a program for screenplay writing which does all of the formatting for you. (There are other programs which do the same thing, I think, and they would probably be just as good.) Whats cool about it is that the structure is limiting, in the good way-- structure gives form, and form gives power, after all. When you have a constricting format like screenwriting has, it really focuses you, and it strangely makes it easier for you to tell the story you want to tell. For me, when I try to creatively write (like a short story or novel) I spend most of my time stressing about how I'm gonna tell the story-- "he walked in" versus "he ambled in" versus "he stepped into the room" versus whatever-- and screenwriting, with its emphasis on simply what happens and not on how it's expressed, removes that burdened. And because films can't show thoughts, I don't feel the need to express the internal aspects of characters.
Lots of times I'll just write up a scene or two, or even just turn something that happened in my real life into screenplay form. I really recommend it, it's a great outlet for stress-busting and creativity.
(Uh, Final Draft didn't pay me, or anything.)