GNU Spell, a clone of Unix `spell'

 GNU Spell is a spelling checking program which prints each misspelled word
 on a line of its own. It is designed as a clone of the standard Unix `spell'
 program, and implemented as a wrapper for Ispell.
 .
 Spell accepts as its arguments a list of files to read from. Within that
 list, the magical file name `-' causes Spell to read from standard input.
 In addition, when called with no file name arguments, Spell assumes that
 it should process standard input.