It is inspired by the date range selector at Google Analytics, and will let you select a date range with a minimum of clicks.
To add to any page, simply include the small .js file and style sheet, and make some small changes to your form.
I've tested it with IE7, Opera 9 and Firefox 2.
Take a look at the included example file, usage should be self-explanatory. A small howto is here
Project page here