In their book The C Programming Language, Brian Kernigan and Dennis Ritchie say that the first program every programmer should write is a program that writes "Hello, world!" to the console. Then they give the second program that produces a fahrenheit/celsius temperature conversion table, with fahrenheit temperatures every 20 degrees from 0 to 300 and the corresponding celsius temperature to the nearest degree, each pair written on its own line with the two temperatures separated by tabs.
