I Write, Too – You can see some of my writing (and art) in Hack/Slash: Trailers Part 2 from Image Comics, as well as an upcoming sci-fi anthology comic called Fearless Future, being published online soon. I’ve written short stories and screenplays, but nothing’s sold just yet.
Writing Tools - I currently use Pages on my Macs as well as this great, free program called Celtx that is designed for writing screenplays, teleplays, comicbook scripts and more. I find it more robust than similar programs like Final Draft that cost hundreds of dollars. Celtx is available for your Mac or for Windows or Linux.