There are dozens of built-in fields, such as the date and time field above (which can be formated by putting the correct string between the curly-braces).
Some useful fields are the hostname (h or H), the user name (u), and the current working directory (w or W). There are many ways to get the date and time, or one or the other, in addition to the 'D{}' shown above.
Living Color
Setting the prompt also allows you to change the colors of the text, even the color of the background. It's a bit of black magic, but add the string '[