Consider the operation of a line of supermarket checkouts and the profiles of customers and their shopping baskets. Use a random number generator to create the data for these profiles if you wish. Maintain a prediction of the order in which customers will complete checking out and leave the supermarket.

A program to help a Computer Dating Agency.  The program consults a file of information about people - their name, age, sex, interests and dislikes. Given information about a person, it finds others that are suitable for introduction.