ahhhh! lets see:
Take some worksheets with you... place in plastic sheet protectors... play games like hangman, tic tac toe, etc....
Take beeswax with you.... make something...guess what it is
If you know you are going to be stopping soon, (don't let the kiddos know the first time) Have them count.....by 1's, 2's, 3's, 4's, etc... until you get to the exit. How high did you get? Let them have that much in coins (or $1.00 per stop) to add to their "splurge" money.
