I just ran across a service that might be very useful: Google Voice
It’s free to sign up, but some of the services do cost, so read the user information carefully.
The most important feature, from an author's point of view, is that you can leave a voicemail message for yourself and Google will transcribe it and send it to you as an email. It’s kind of cool. What this means is that you’ll be writing like Raymond Chandler, and many other very good writers, who dictated their work. This has the great advantage of using your actual voice, hopefully sounding just the way you (and your imaginary characters) speak, as opposed to write.