Here's what I use:
Pages: For mac. Took me trying out a few others before I decided I liked this one best! I needed a nice one to use on my mac.
Fan Fiction.net : Now mind I haven't updated anything on there for AGES, but I used it a lot back in the day!
Fiction Press.com : Again haven't touched it in ages. In fact I think I don't have anything on there anymore. Think I took it off. But again, used to use it a lot.
DeviantART : I sometimes would post writings on here as well. Did have a writing group that I haven't updated in years. XD
Notepad/Text Edit: I would sometimes write in these if I happened to be bored!
Word: What I used on my regular PC.
Wordpress App: I sometimes use that as well for blog stuff!
Paper/Notebooks/Pens/Pencils: Good old traditional stuff! I sometimes like (okay more often then not) to use plain old paper and pen. I also store it in a variety of notebooks, folders, binders, and a file storage thingy. Also have a lovely writing pen I got from my mom for Christmas, a space pen! Its also engraved with my name and "Dook, Dook, Dook!" XD