SITO is totally open to creative collaboration of all types, not just graphics. True, most of our projects are graphical. In fact, the most active of our projects are grid based. But even the grid-projects have an element of writing to them. Each piece has a title which somehow matches up to those around it. In Gridcosm in particular, this turns out to be a kind of dada poetry.
However, we do have narrative graphic projects. For example, we've done a comic book called Impulse Freak, http://sito.org/synergy/ifreak ... There's also an online version of IFreak that was originally developed for HotWired. Modular narrative, but narrative nonetheless.
One project that never really got to a point where I wanted to make it public was called Trangaea, a collaborative storyworld. You can see parts of it at http://sito.org/story
So, yes, we're interested in the written word. Part of that interest is evident in the development of this, the Discussion area. Words are quite important.
What are your ideas for collaborative writing projects?