I haven't had a large writing project in awhile, but used Scrivener version... 1? maybe 2?  This was a few years ago and I see they are on version 3 now, which I haven't used.  But really, really liked it!  

If you're just talking about writing RP posts, it might be overkill, but if you're working on a book or other large project, it's nice. :)