Group writing

I use various little methods for making writing less of a chore for Ss. The old classic, "It was a dark and stormy night...,"  is way more fun if you do it in groups of 4 or 5 writing a sentence at a time; it also offers writing and error correction practice in equal measure.
A Shaggy Dog Story is another way where Ss are given a list of words by one S and they have to hide them in a written piece from another S (groups of 3)
Writing as another person, a fictional character, or even an abstract concept: eg Write a letter from Monday to Friday (pretending to be Monday)
Dear Friday,
I'm writing to ask if you'd like to swap jobs for a while...