Teaching a writing class is significantly less fun than teaching oral English. However, the opportunity to gain insight into student's thoughts is priceless. Here are a few past favorites:
"Growing Up Country", in which a student describes her childhood schoolhouse
"Summer is a Season for Show", which contains the awesome line "short-shirts are flying in my eye"
And finally, "You Could Write a Book about Each One of my Thoughts", which is not technically a composition, and wasn't technically produced in writing class, but remains one of my favorite student slip-ups of all time.