There are many other datepickers available on the Internet...this happens to be the one that I wrote. You are free to use it in any way you'd like in your own applications. If you're feeling nice, you could even include my name with the code.
The format of the datepicker (color, fonts, etc.) is easily customized using CSS. The date format can be customized using either global variables or each time you call the function that displays the date picker (see the code for more information). Enjoy.