When caught in traffic or waiting somewhere, here's a game the whole family can enjoy. Beginning with letter A (or pick any letter!), go through the alphabet making letter sentences in which all words start with that letter. For example, the letter E might inspire: Eager Ed ended every evening eating eggs. Sentences need not be sensible, and allowing words like the, a or with makes it a bit easier. Besides honing verbal skills, the game is fun—it encourages kids to think in new ways, consider unusual and even foolish ideas, and that is a prerequisite for nurturing a creative spirit. 
A word of caution: the entire alphabet can become tiresome. Stop when your kids have had enough. It's counterproductive to force your kids to follow paths that should, by definition, be freely and joyfully pursued. Take The T Tomorrow!