We have been using google docs to do this. A group of two people from our class and two from theirs write the story together, at the same time, over the internet! It is very cool.
If you'd like to check out some of our stories, please visit their blog by clicking on the link, since their teacher has kindly put them up!
It has been lots of fun for us, learning to write in a different style, and getting to work together with kids we've never met! Thanks for including us, Room 9!