The proper, or most common way, to set the date in the United States is MM/DD/YYYY. Two digits for the month (ie- 12 for December), two digits for the date, and four digits for the year. The leading zero of the DAY (ie- 03 for March), can be omitted. It can also be spelled out, such as February 8, 1990.
Pieper is correct about the date for the U.S. But we are pretty much the only ones who do this (similar to us not using the metric system). Most everywhere else it is the day then the month then the year. For example today is November 19, 2010. In U.S. it would be 11/19/2010. Elsewhere it would be 19/11/2010. There are other variations which put the year first, but the most common is dd/mm/yyyy.