Best Practices-- Date Control

While designing web pages you come across Date filed (Ex. releasing dates, stocking dates, order dates, shipping dates,birth dates,wedding dates, you name it.) many times.

I realised that there was no real consistancy with dates, in all there is about 4 different ways that a user can enter in a date. That made me think, why isn't there a standard. Surely there has to be a best practice in relation to accepting user dates.

Dates are of Two types :
1. Known Date :A known date is where the user is fully aware of the exact date, like a birth date, a start date, an expiry date. Known Dates are usually entered by the user using the a form element like a drop down box or even entering the text into a textbox.

2. Fuzzy Date :A Fuzzy Date is where the user isn't excatly sure of the date they have in mind and need prompting from the graphical interface. The date could be the first weekend in August or the Monday before the 26th of December. To properly assist the user with this type of date, Calendar functions are used and the user select the day they would like.