One ketchup and pickle folder. found this incredibly adorable idea somewhere for using "ketchup and pickle" time - if kids finish early, they either "ketchup" on unfinished work or the may "pickle" another activity to do.
For teachers: Do you ever have a student that just needs to get out of the room for a minute and get a new perspective? Give them "The mysterious envelope" to deliver. (I like the "mystery student" idea too)