I came across this application the other night, and it looks interesting. It's geared towards script and play writing, but can be used for almost any type of creative writing you can think of. It can help you keep track of characters, scenes, and so on.
Just wanted to let you know about it. If you interested, check out celtx.com
And one massive note for the end: I am not affiliated with te producers of this software, it is available for Win/Mac/Linux in several languages, and the location of the thread was approved prior to posting. If it turns out that it really should be moved, my apologies.